How much lift with stock magnum roller lifters?

Was he able to get all the slop out? It really wouldn't matter I wouldn't think as long as you included said slop when you adjusted the valves. Just make sure you were pressing down on the pushrod side to take the slop out.
As I recall, he had the perfect combination of internal pieces, using disassembled chevy hydraulic lifters, to take up the cavity space completely to the retainer ring. The end result was essentially no slop. When I get home tonight I will go have a look for the one he assembled to show me the process. The combination of parts went together like Lego! Lol