Solid roller cam Vs Hyd flat tappet

Just swap to the right springs for the cam you WANT to run.
You really need to want t9 run a solid roller, and build the motor FOR a solid roller to make the investment worthwhile. You don't want a solid rolle4 bad enough.
Tho, if you DO HAVE a roller block, a hydro roller would be the way I would go.
(But you will STILL have to change the springs!)