[Cliff R]

An easy way to convert to screw in studs is to obtain a block of aluminum wide enough to span across two adjacent studs. Drill it to the diameter of a stud or 7/16" in a drill press. Come over on center the exact distance of the adjacent stud and drill a straight hole then run the desired tap thru it. For Pontiac heads you can go up to 1/2" and buy conversion studs or heli-coil back to 7/16" and use straight wall studs.

One stud is pulled and your aluminum block slides over the remaining stud and lines up the tapping operation on the adjacent hole. Once complete install a stud there, then pull the stud you just used as a guide, slip your tool over the screw in stud and tap the hole you just pulled the stud from. Work your way down the head swapping your guide tool back and forth until you get all of them tapped for screw in studs.

I made a block for SBC heads nearly 50 years ago and another one for Pontiac heads about 25 years ago. Don't use them much these days as I've been sending heads out and let folks who port and rebuild heads for a living do all that stuff, but they are pretty easy to do yourself even if you don't have access to a mill........Cliff