Is it an "L" block? I've upgraded all my MIJ Socals with the regular brass blocks, but they are setup slightly raised to float. I had no problems with clearance using the 37mm blocks. The only way mine will hit the cavity is if I'm trying to pull back on the bar too far. It's still got some pull back range though, plenty for my uses. I can bottom out the trem bar on a dive without hittin the cavity. The blocks I have are the same size as the blocks from Chub, one is actually from him. I did find the 42mm block will impede some movement on the dives, but it's still not a factor for my uses.