Got a decent valve spring compressor

What is the throat depth on that clamp? Center line of the clamp to inside face of the beam? I don't have a head hand to measure the needed distance.

I loaned it to someone, I asked them to take a measurement when they get a chance tonight.

Your turned, milled piece is a dead ringer for mine. Only difference is my c-clamp isnt adjustable. It has a eight inch long screw, so that hasnt been a problem, works like a champ. It is heavy, however,lol. Whats nice is, its still perfectly usable as a c-clamp!

The nice thing about the adjustment bit, is not having to thread/unthread the whole way. You can compress, uncompress and then get it out of the chamber just by adjusting it. I was pretty happy with it, should have made the windows bigger, I had to fight a bit to get the keepers in