[Mach 1]

I think your wasting your time to port to a mirror finish on the stock intake, mainly because you cant access the entire runner.

Get an edelbrock where you can remove the cover for access if your going to spend that much time with a grinding tool.

You can go mirror on EFI intake because there is no fuel flow. Thats the reason to not port the intake port on the head more than an 80 grit finish, some turbulence is desireable where the fuel and air are traveling together.