I prefer to have the heads on the motor with its head gaskets. That way you can see where You actually need to clearance the pan gasket at the ports.

Do one port at a time, put it on, you can press it on by hand and try you best to mark that port with a marker. Shave and recheck, until that ports fit is how you like, then move to the next. Make sure you press fit the pan to the same spot every time. I even Pinned mine to the head at all four corners, two on each bank.

I used a dremmel as well and maybe even some cutters. Use a Fine dremmel bit as if it is to rough, it can Grab the flimsy pan gasket and bend it. Most times you can bend it back to original shape no problem. But, you really want to Not have to do that if you can.

Ive never had to restart with a new pan gasket.


Edit, I don't shave the gasket while its On the head. That's just to check the fitment after marking it and shaving it.