It's possible to build a stovebolt engine with non-original parts- - - - -connecting rods and rod bearings for a big block Chevy V8, pistons for certain Ford, MOPAR, AMC/Jeep, or Japanese diesel engines- - - -roller valve lifters for a big block MOPAR, and non-standard main bearings. Unfortunately, that requires something that's even more scarce that OEM stovebilt parts- - - - -a competent machinist!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!