Hydraulic lifter preload...who really checks this?

As AJ said, his lifters had over 0.200" of plunger travel. And post #12 gives the reasons why the manufacturer provides so much travel: for future maintenance [ valve jobs, heads milled, decking ] & factory tolerances. For your average performance engine, anywhere within the 0.200" range is ok. If the engine is to see high-er rpms, setting the prod cuphigh in the lifter risks pumping up the lifter & pushing the prod cup out. A stronger circlip here is the answer. As far as rocker geometry, there are different schools of thought.