318 with random parts.
As far as the life of the lifters, that's partly in the break in and even more in the oil additive, you must use a zinc additive or replacement in the oil to keep the cam from wiping out prematurely. Or just bite the bullet and put in a neat roller system. Since the factory rockers are adjustable, all this old stuff is still cool to have and use but unless you're into the nastalgia of it there's a lot of better newer stuff to be had.
Most modern aftermarket hydraulic lifters are junk. Doesn't matter what is or isn't in the oil. Lots of very experienced people have had problems with them in various ways. Often having to go through several sets of lifters to assemble a decent set. Even when a cam survives break-in, many hydraulic lifters lose their function and begin either tapping or causing trouble at moderate RPM which shows up as power loss.
A mechanical flat tappet cam really has few drawbacks and the service required isn't near as often or as difficult as many make it out to be. With proper oils and moderate spring loads, mechanicals can go quite a while without service, and have no added complexity of an internal hydraulic spring, cup, and check valve that's failure prone and sensitive to manufacturing hygiene and tolerances.
Roller cams aren't a fix-all. There are issues with distributor drive gears, cam core materials, heat treats, etc. Bronze drive gears are fast wearing, and melonited (melonized, qpq, nitride treated, etc) gears are hard to come by and few cam companies will warranty anything run w/o a bronze gear. Stock hydraulic rollers aren't an issue, but those don't off the performance most are after in a hot rod.
Everything is a trade-off, and using flat tappets is not a 'nostalgia' thing, but rather a common sense thing to ensure a sustainable engine assembly.
