Hi Ian,
I wouldn't use any higher than 8:1 or thereabouts with the fuel we have to put up with [in Australia, anyway].
These engines have a tendency to ping, just look at any alloy head combustion chamber, some look like a jackhammer has been at work in there.
If an iron head, do a little porting and use Rocket size valves. A 357 cam is the go for power but you may have to modify the cam tunnel if you go that way, just needs a little opening out to clear the lobes in the early cases.
Musky may put in his two bob's worth on compression ratios, he likes them high.
Trev.