I believe Johnson Hylift sources these lifters to Comp Cams which repackages them as the Comp Cams Pro Magnum Lifters

Lifter preload should be set to .002”-.004” (hot settings) - LINK

Best deal on Johnson Hylift lifters: https://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=5650281&Main=5649254