lifter preload w/adjustable rockers

I've been doing some research into this and can't quite find the answer I'm looking for. I have stock 273 adjustable rockers and I wonder how far to turn them after 0 lash to get the proper lifter preload. I've seen anywhere from 1/4 to 1 1/2 turns. Which is it or what's the best way to measure for preload?

360 LA with Oregon Cams hydraulic roller cam with stock hydraulic roller lifters. Gross lift is .539 int & .558 exh, 235/247 duration @ .050".

Thanks!