Reply to "Lifter niose"

Listen to Kelly. Comp Cams makes some of the most commonly-used solid roller lifters, and their Tech Reps say not to expect more than 4000 street miles from these racing parts before they break & destroy your block. Most other cam grinders won't give mileage estimates at all.... If you need help, there are probably local race shops near you that could set them up while you watch. After that, you could do it yourself.
Don't expect to tighten the setscrew and have it hold; you will rip the hex out of the allen screw before it's tight enough. Instead, tighten the setscrew 'pretty tight', then tighten the lock nut, then turn BOTH the allen wrench and locknut together another 1/16- 1/8-turn. This while you're balancing a feeler gauge strip in the gap between valve stem & roller. Not much fun to get right in a Pantera engine bay.
But before you rip into the engine, remove a valve cover, then start the engine and listen & watch the valve action; it's possible that you simply have one (or more) bent pushrod and replacing the damaged one(s) will quiet the noise. Much easier than doing all 16. Good luck- sounds like a nice motor.