From the few years I've lurked on this board, it's common for a high mileage 300 to make a little lifter noise - mine has since I bought it 3.5 years ago. When do the lifters make noise? A little ice cubes in a glass sound at start up is ok as long as it doesn't persist - meaning take it for a test drive. If the noise continues after a few miles (10 or so) and you notice it persists at idle, then be concerned. I've put on over 50K mi on my old '79 stocker, have crept past 220K and have had no other problems other than a little lift noise at start up.
I was once told by a machine shop the noise was due to increased valve train tension, being that the valves begin to seat deeper in their seats....replacing the lifters won't fix it. I personally think it's due to low oil pressure at start up. A high mileage engine always benfits from a good warming before driving.
If you really think swapping lifters is the way to go be warned. A high mileage engine with the original cam may not have enough pattern to break in a new set of lifters - they won't spin in their bores properly or at all.
The 300 is a tough, dependable motor. Don't fret on a little momentary engine noise.
try a thicker oil... worn engines have larger gaps between parts, so to compensate for that, a thicker oil would be the benefit. this will save your engine down the line. i suggest 15w30 or 20w30. you can also run 10w40 but throw in a bottle of Lucas Oil treatment.. thos stuff is sticky and very thick, so it will stau in between larger gaps for a longer period of time, quieting or even silencing any type of engine-related startup noise. i've used both methods in the past and they work great. the thicker oil method is the cheapest, being that Lucas oil treatment is aroun $7/quart (you need one for everey 4 quarts of oil)
if you do go the lucas route, i suggest pre-heating it to allow it to flow easier cause it takes 2 years for it to spill out. a good thing to do when your at the very end, throw in a bottle of 10w40 inside the lucas bottle, mix it up a bit then throw it back into the crankcase.. that takes all the residue out and makes your money's worth.
HEY ERIC!!! lol i've been a member for quite a while now.. i originally joined cause of my ranger, but only made one post up until 3 weeks ago when i got this '86 f-150 for FREE (lol) and so far its been a good truck, just the usual bugs here and there but no biggie.
anyway you might be able to repair a collapsed lifter by completley washing evereything out and making sure everey oil passage is clear. then in regular motor oil, let the lifter sit upsidedown (making sure the lifter isnt collasped) submerged in oil for 24 hours (i like to do 24 hours, others do less)
this should bring the lifter back to life.
I would go for it if I were you. I'm loving this truck alot.. its strong, sturdy, and can haul some as$ for being a 6! propertly tuned, it can do some mad burnouts!
also as a coincidence, my f-150 is also now going to be my work/winter truck! this winter i will (hopefully) get to work on rediong the entire body on the 'queen. i'm hoping next summer she will be like new again!