I haven’t done a stone valve job since the early 1990’s.
You can’t possibly do the same work with a stone as you can with a single carbide blade cutter. Not even close.
Some basic rules are never, EVER use a radius on the intake seat. It looks wonderful on the flow each and kills power. Every time.
The top cut is critical. It should be as wide as you can get it and you need to test for the correct angle. Both the intake and exhaust seat need a top cut. A top cut is not sinking the valve.
More angles on the intake seat isnt always better. It depends on valve and port angle. What works on a 23 degree valve angle head may not (and probably doesn’t) work on an 18 or 15 degree valve angle.
Throat percentage is critical.
