When I did a mild clean up on a previous set of vortecs with stock valves.
The flow was 228cfm . Got it to 232 some odd with a general but mild bowl clean up.
I was not looking for or after a big gain. Wanted to evaluate them in stock form and the cam used was only .442" lift.
Use common sense here. The as cast shape is quite good as is. Especially for mild camed motors.
If when you go to a larger 2.02 or 2.05" valve and the cam gets a lot bigger you can open up the port and bowl more to good effect.
You can be quite agreeive on the exhaust side porting but do not make the exit huge.