roller cam rip off

one thing on regrinds for rollers..is make sure you measure your roller lifter in relation to the oil galley ports..and calculate it off of the base circle.
if you have the base circle diameter made smaller to change the lifter profile and or add lift...this means the lifter will run farther down in the lifter bore when its running on the base circle/valve closed.
..this could uncover the oil galley feed holes and you will loose oil pressure.

as to the running a roller lifter on a straight 509 cam lobe profile... the valve events on the roller will not match the valve events on a flat tappet..if your using the exact same lobe profile for both sinarios.
...with a roller on that lobe you would have a worse valve events..than the tappit lifter... the came would essentially be smaller....not in total lift..but in all the other numbers/events
just get a roller turned to meet the needs...
I recommend having your cam built to match the flow chart/graph of your heads/valves
fwiw..
be well