What do you mean by 3 angle valve seats?
The first step to improving the flow of cylinder heads is often overlooked. This is a big mistake as a good quality 3 angle valve job will make a significant improvement in port flow at all engine speeds.
For most V8's, seat widths of 0.065 inch for the intake and 0.070 to 0.075 inch for the exhaust (both at 45 degrees) offer optimum flow, sealing and excellent thermal transfer to keep the valve heads cool.
Despite widespread belief to the contrary, seats narrower than these don't improve flow and can cause valve overheating. Finally, flow can often be further improved by adding a 30 degree back cut to the underside of the intake valve (see image below).
Grinding the valves and valve seats sounds simple, and it is. But if you stop there, you'll be cheating yourself out of a lot of power. A relative minimal additional effort spent working on the port shape can produce very worthwhile power gains.
Both our Stage 1 and Stage 3 cylinder heads have 3 angle valves.