Hydraulic lifter preload...who really checks this?

Basically what you're saying is you've never properly built an engine. The few engines I've built are in the opposite end. I've scrutinized every detail.

Hughes has instructions on how to set all this stuff up the right way. It involves setting the proper wiping path across the valve face using shims, and setting the rocker adjuster balls to the proper amount of extension beyond the rocker body. Its a tedious job but worth it as you'll ensure proper geometry. Be warned those rockers often require clearancing around the valve springs.