Just read this thread...
That's a real interesting situation you're in james, really got me thinking....
Anyway, for what its worth, here's the timing set up on mine and the cam specs. Its 11.5:1 comp. Funny thing was when i initially set up my timing i put WAY too much in it and it was pinging its brain off, so i started backing it down to where i thought it was 12 degrees - from about 15. Still pinged its head off though. While getting the dyno done, we went over the timing again. Little did i know that apparently "some" (feel free to correct me here) of the early red 6's had the big mark on the timing cover indicating 6 degrees.
So my 12 degrees was still 18!
I know your timing is a lot greater than this but it shows how easily you can get caught out.