Do not grind the valve guide boss off, just streamline it!
I have ported 351W heads and Trick Flow Aluminum heads, I would suggest just cleaning the ports up without removing much metal. Finish the intake ports with 60 grit and make the combustion chamber and exhaust ports as smooth as possible. If you polish the chambers be sure to remove a minimum amout of material.
The studs are usually 3/8" or 7/16" at the top, but I am not sure about the threads that go into the head.
Check out this website for porting tips
Good Luck
http://www.sa-motorsports.com/diyport.htm
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67 Fastback - Arctic White Pearl paint
351W ,Trick Flow Aluminum Heads, Edelbrock TorkerII, Comp. Cam, Performance Automatic C-4 Trans, 3.55 gears, Front Disc Brakes, 1-1/8" Fr. 3/4" rear sway bars.
My 351W Fastback
