out of curiosity, i dug out my old notes about the studs i was seeking last time i needed some. one of the sets i have is 108mm long from the underside of the shoulder to the end (so, basically thats the length of the lower half not including the shoulder). those studs fitted in one my blocks fine with plenty of thread engagement and the shoulder with O ring fitted sitting just below the deck surface. those studs however, were too short for another block - pulling the deck down as i mentioned earlier and not having a long section of thread engagement. i tried burtons but thier studs were the same length. those from SCS however were longer (115mm) and had more engagement and could be torqued into the block without the shoulder touching the counterbore.

i never did get to the bottom of the issue which, on the face of it, suggests that the block deck height on one of the blocks is about 10mm below spec and counterbores for the shoulders machined deeper accordingly (unlikley), or the tapped holes in the block's saddle are somehow different depths. maybe one is a turkish block and they are different?

l'd recomend that you get studs from the same place you get the machining done