take your time. You don't have to get as close as I do. You've got the right idea. I was nervous myself the first couple of sets I did. In fact, I still am very cautious. Porting heads with a hand held device is an art. You have to know what it will look like when you are finished.
My first set I ever did was a set of J heads with 2.02's well over 20 years ago. Yep, I nicked one seat. I lapped my arm off trying to get rid of it.... LOL.
Thanks I appreciate the help. So basically you won't to open the bowl up the same size as the seat and open the seat area (right against the seat) the same size as the bowl. Without making the bowl larger than the seat. Correct?