I run them on my 470 stroker. I got a set of the first run of them. I welded up the chambers to run the gaskets I wanted and then ported them. I had my machinist give the a 3 angle valve job, narrow the seats and shave them .075.
I had to change the retainers and locks after running them for a while.
It runs 6.40s in the 1/8th. I v'e been happy with them.