I don't know that your motor is relegated to being slow with low compression. If I could get into the 12's with a less than 8 to 1 compression 318, then you should be able to do the same with a 406 (or whatever size it is) if you have a decent induction and exhaust. I would run the WOT timing up around 40*, or at least run a timing loop at the track to find out where it runs best. Don't ever "assume" you should set it where somebody else told you to set it or what you read in a magazine. If there's one thing I learned running a 383 with 906 heads it's that it likes lots of total advance because I guess of where the plugs are located in the combustion chambers, much the same as a 1st gen SBC.