Magnum Head Rocker Arms
A magnum rocker will yield 1.6 or better at the retainer, shim up a lifter solid and check with a dial indicator, even with pushrod angle and all. The only thing I had trouble with was the factory pushrod, they would bend at low 6000 with a 325 spring and 550 or so lift. I’m sure the lobe configuration could move this up or down. A simple set of aftermarket pushrods always solved the problem.
The rage on the Ram pickup forum is to put a set of 1.7 high dollar rockers on your stock truck, I really wonder if the juice is worth the squeeze on that, I honestly doubt it but I may be wrong.