Yes, the Crowers do work well on mildly modified engines.
As long as you "don't" over rev the engine beyond 6,250.
The tips have self aligning rollers that can walk off the valve retainer, therefore, the valve can become unhooked and drop into the cylinder causing catastrophic engine damage.
We have used them in the past. You can order them from Crower w/out the roller guides.......... With the heads off you can shave .100" of the rocker pad area and run them with a guide plate.
Of course, you will need hardened push rods. Try to use the .060" wall thickness pushrod (not the .080") for less valve train weight.
Regards,
