Flat tappet to solid roller...

The issue is that lash pounds the needle bearings in the roller lifters, they go flat/out of round, then skid, then everything rapidly goes to Hell after that. Improved pressure oiling lifters and bushing lifters are methods to counter this. This isn't a maximum kill effort, so there's not going to be the spring pressures that accelerate these issues, but it's still something to concern yourself with.

If you switch to a roller cam, you're going to need new valve springs. Roller lifters are heavy and use aggressive lobes(otherwise what's the point?) and will need serious springs to control valve motion. Failure to control the valve train properly will rapidly blow everything up. The Chrysler stuff has a nice .904 tappet, we can use pretty decent flat tappet cams.

The Comp MM lobes in the 240 degree range have .550'ish lift with the 1:5 rocker, but if you currently have 1.6 ratio, going to 1.5 is a step backwards.

Roller lifters and cam profiles will make more power, certainly, the question, as always, is the power worth what you're willing to pay for it? S/F.....Ken M