My last 2 engines had Stave VI heads, both had a bunch of work. These are the current set. I forget all that has been done. The were used in a magazine article I believe and were on a members spare race motor. As you can see the ports have been massaged some. From what I understand these head will work, they just require some modifications. I posted on them last year I think. If you search my user name you might be abe to find the info. Maybe somebody here can refresh my memory.