Solid roller lifters

In search of others thoughts on lifters.
As my big block build progresses I am now in a search mode for the proper lifters to go with this. As said in the past,
383/496 molnar crank 4.25 stroke, 6.535 rods, Trick flow 270's , indy intake
Roller cam custom grind. Any HELPFUL tips or advise welcome.
This may be a dumb question, but, how much valve spring pressure and what kind of service are you subjecting them to?