My favorite Ford engine is actualy the good old reliable 390. Unfortunately, it costs a boat load of money to build one to do what the 460 does with out any add ons.
I had a 390 in my truck, and I went to a 460. I realy miss my old 390 and have been researching long and hard on how to get an FE that will hang with my 460.
There is a guy that has figured out a way to make a 390 have a 427 bore. I'm seriously looking at using a 391 FT block, with that 427 bore, and a 428 crank. It would yield 454 cubic inches. That would be almost the cubic inches of my 460 with the bullet proof FE design.
As far as 400's go......I wish they would....away from me of course.
It seems very odd to me to hear 400 in the same sentence with performance. And trying to compare a 400 to a 390 or a 460 is just down right hilarious. I know some guys have good luck with 400's, and I don't want to end up in a war with them.
I think it boils down to this....most of us here are on tight budgets. A 390 can be built to make acceptable torque on the cheap. A 460 has so many cubic inches that you can basicly do a stock rebuild and have a lot of get up and go. A 400 can also be built to hang with the big boys, but if you figure up how much it would cost, it's just more cost effective to do another engine.
Right off of the get go, a lot of 390's and 460's came with 4 barrel intakes, if you don't have one, they're dirt cheap to get. A 400, to my knowledge, never came with a 4 barrel manifold. In order to go to a 4 barrel, you have to go aftermarket and spend a couple of hundred. On the 460 and 390, if you have a 2 barrel, you can upgrade to a 4 barrel for 50 bucks or less at your local U pull it yard.
You guys sit back and think about it a second....Most of you can't afford to build a 5,000 dollar engine.....so you cut corners where you can, and try to get all the torque and horsepower for the cheapest amount of money. The easiest and cheapest way to do that is cubic inches, or engines that were pretty hot right out of the factory. A 351M/ 400....was neither.
Doc

 

Hope this helps

460 swap
1973-77 f-250 4 wd with 360-390 engine and c-6 transmission
will the 460 bolt up to the c-6 from 360 engine?
no, different bolt pattern

will i have to change the exhaust? yes

will i have to get motor mounts for the 460? yes

will i have change the motor mount towers on the frame ? yes towers for the 360 set to high for the 460 block.

will the alternator or power steering brackets from the 360 engine fit the 460? no
ford did not offer the 460 as a option in the f-250 4 wd trucks from 73-79.

 

to help with this if I may the frame perches from the 73 2wd would swap into the 73 4x4 but on your situation I would measure the frame width of both trucks, and look closely at how they are mounted to the frame basically compare them and see if the frames are close enough to do that swap of hte frame perches.
This thread digressed into which engine is better the question isn't would a 460 be a better choice than the 390 but rather can he put the 390 into the 78, and I believe the answer is yes but since you have the oppertunity to look both trucks over just measure everything. I have had both 390s, and 460s, and am currently running a stroker version of hte 460 but if you have the good 390 you have a great engine and I think you can make that work. it will take some thinking and such but shouldn't be too hard to do since you already know about changing the output shaft of the tranny and the radiator should bolt across which would supply you with the correct cooling locations for both the engine, and tranny, fuel lines aren't a problem at all about hte only thing I can think of is if the 390 has a front sump pan you will need to switch that to a rear sump or atleast you should in order to use it in a 4x4

 

Ok thank you lol, that's the kind of info I was looking for. If anybody know's for sure I'd love to know otherwise I'll just get the tape out when I get the chassis. Oh does anybody know if I'd need the long or the short tailhousing for the c6 if I'm putting it in place of a 435? I can't remember off hand. To hopefully answer the engine debate. I've thought about building the 400 but then I'm looking at quite a bit of money to do that, and I could be wrong but it costs a lot to make a build motor reliable. The 460 route. I'd love at some point to put in a 460/aod combo. Yes I know it's an overdrive but most of my road time would be on the highway headed to the coast and back. The 390 it's FREE and it has an auto attached to it, they're a good motor I know people to get lots of parts from. Plus I'm not really looking to build anything narley so I don't need a bunch of aftermarket stuff. I just want something with good power to go play with FOR NOW.

 

Well on the 77 F150 chassis my race truck is built on I used the short shaft/adaptor when I replaced the 435 that was in there with a C6 if that helps any.

 

Ok, how hard is it to slide the tranny crossmember back? I'll look in the morning to see if there's any holes further back. I know there's CV joint issues with the tranny pan with short tail. Plus lifted truck, longer drive line in the front would be nice.

 

I don't know a whole lot about 4 wheel drives....but I can promise you this....the only way that 2 wheel drive motor stands will fit in a 4 wheel drive truck is with a welder and cutting torch. You may try to locate inline 6 stands from a 4 wheel drive. On 2 wheel drives, the inline 6 and FE interchange.
Doc