Valves only bend when they hit something or get so red hot they are near melting. It sounds like you really got that puppy hot, and that end cylinder is furthest from the carb and the leanest, so it got the hottest. Also you had a carb leak which aggravated the lean problem, as no doubt that also caused a lower fuel level in the carb. And a coolant leak which made it even hotter.

Being you have the head off, take it to a machine shop, and have them put one valve in it and lap the seat for you. You wouldn't want to put it in yourself, bolt it all back together, and have it leak, and have to tear it down again. Whatever they shop may charge is cheap insurance, as the engine sounds carboned up and it would be easy for that valve to leak on you and not seat.

Consider yourself fortunate, many engines have bit the dust in a situation just like that. I've pulled down many where the owner would describe an overheat scene just like yours, and they kept driving, and cracked a head, or cracked the block between cylinders due to heat. It happens. The pile of cracked head and block cores outside our garage attested to it.

 

The metal build up on the valve is where the guide and valve scored each other. It happens when the valve gets really hot and swells up until there is no play in the guide. Then metal to metal happens and you get the scored guide and valve. You have to polish that roughness out of the guide. A pencil and some emery paper will probably do the job. Just take your time and it will smooth out. You have to have a new valve. The 10 bucks you spend will be worth it. If you have the dough take the heads to a shop and have them check them for cracks. If not then clean around the valve very good with a knife or scraper. Look especially hard at the areas between the valves. The skinniest portion of the head between the two valve seats is the most common area for them to crack. If you don't see anything obvious then bolt it back on and go to town.

While you have the heads off and a valve spring compressor you should spend the 8 bucks or so and put new umbrella seals under the springs if you can afford it. That will also give you an opportunity to inspect the seats much better for cracks. Just be sure and oil the valve stems before you put them back in with motor oil. While you are in there you can take a scraper and scrape any built up carbon off the back of the intake valves. Just don't gouge the seat area.

As for the bottom end. That is up to you. You say you are bucks down so I would leave it alone. But I would definitely change the oil. If it held oil pressure before, then I wouldn't worry about it. But if you were having oil pressure problems then I might pull the pan and check a rod and main bearing to see what they look like. Then go from there.

As for the front u-joints. Yes they are a pain, but not beyond the knowledge and skills of someone who can pull heads off and pull valves out. Finish the motor and make sure it runs. Don't be cheap on gaskets, that valve and guide or oil. Everything else you can do what you have to do to make it run. Torque the head bolts then wait a few hours while you are putting the rest of the motor together, then torque them again. If you had a vacuum leak under the carb you should fix that while you are in there. On the radiator just take it to a radiator shop or somebody who knows how to do those things and have them re-solder the tank back on. Now that it's cold it should be just fine. It shouldn't cost you more than 40 or 50 bucks to have that done at the most, might be more like 20 or 30. That's a lot better than what a new radiator will cost you.

Once it is running then you can tackle the u-joints. The parts if you do it right will run you 20 each for the u-joints then whatever else you need. You will definitely need wheel bearing seals and the socket to remove the wheel bearing nuts. You can rent the socket at most autozones. If you go cheap on the u-joints I think you can find them for 10 bucks or less each. They will work, but the quality isn't the best for a long term keeper. If you know somebody who has a vise in their garage the u-joints will come out with a little work and a big hammer. Otherwise take it to a shop and have them do it with a press. Maybe you can trade work for something that you do that they need done. Like cleaning the floors or running errands on your spare time.

Don't get discouraged. You had a small bu bu and now you are learning skills and getting to know your truck much better so that you can teach others in the future. Knowledge only dies when you don't pass it on to others.

Good luck. It can only go up from here.

 

None of the local parts shop has the valve so I have to order one.

What grit emery cloth should I polish with to get this smooth?
The scoring seems to be all surface buildup from valve and not actually gouged down into the metal so it should work pretty well.
There does not appear to be any cracks. Going to check for warpage with the side of a steel rule and my long aluminum level.

Of course the parts store was trying to push me to a new head. Said it was only $180. and he could have it tomorrow. I think I would go for a full rebuild before I would buy just one head but first I will try the valve and see how it works.

 

This happened to my boat(302 eng.) due to a failed auxiliary water pump. The engine overheated blowing a head gasket, which I wasn't aware of. While sitting in the boat watching the valves go up and down,and listening to it miss, and everything looking ok, I noticed one of the rocker arms studs slowly getting longer, of course it was being pulled out of the head because the valve stem had rusted and the valve wasn't moving. Didn't hurt the pushrod, tho..........Good luck!

 

If the buildup was all on the valve check the fit of the new valve b4 you mess with the guide.

When you get your gasket set and while you have the valve spring compressor make sure you replace all the valve seals.