Ok...This ought to stir the pot...

Back in the '90s I was running late models first on dirt, then asphalt. I put together engines with World Products pre-assembled heads, cast pistons, solid lifter cam, Speedway stock length pushrods and Crane gold roller rockers.
No optimization of geometry, just bolted it together and raced. Turned the engines to 7000 rpm night after night, never broke a valve spring, never bent a pushrod. One engine had 44 features on it before it finally broke a piston.