I don't remember correctly a great many things. That said, I think I recall that the service blocks from the 70's were drilled for hydraulic lifters. Most of the original factory cars with side oilers were mechanical lifters only and relied on
oil splashing up from the crank. Now that might should be "all" or "many" instead of "most." I am certain that the older high performance FE engines had no juice holes for hydraulic lifters and at least some of the newer service blocks did.
Hopefully someone can set this record straight, for me.
I do know that my personal preference would be hydraulic roller lifters regardless what engine I was building. Plenty of people would disagree. Patrick would. He has a love of solid lifter old school cams. I have to admit I too love the sound. I just never loved adjusting them, and when a hydraulic roller gives better power for my rpm range, there is no point, from my perspective. I never liked reving a big inch engine that I had a ton of money in.