Ok, well, this is a bunch of oop:. I got to install the SBP upgrade head studs and they don't fit. They are too large. By a tiny amount. I can get the studs in a turn or so and that's it. I checked the nut from the kit on a stock stud, it is a bit loose. I have two options, neither I like. 1 is to tap the block out bigger, 2 is to use regular nuts on the stock studs Engine is from BGF and is one of their Z80 motors.