lifter pre load, please advice

Before I try to break in the engine. The pre load is bugging me.

I got a 383" engine.
It´s been square decked, the pistons TDC is .020" down in the cylinder.
Got a .020" steel shim head gasket
915 heads that were milled flat, not sure how much as I bought them in this state.
It also got a hydralic purple 284/484 cam.
Now, I´m using stock pushrod, how likely is it that the lifter pre load is bad?
Do I always need to check the pre load? If so does any of you guys got a
link to "how to do this" ?

Many thanks in advance
/ Lenny