Thanks guys!
We can get Super Unleaded (98 octane) here, which is what I use. Also, I have the Edelbrock aluminum heads, so don't seem to have any pinking issues.
It sounds like I could safely step up to the slightly bigger cam - I have a pretty good intake (Eelbrock Perf RPM, Holley flowed to 890cfm) and exhaust (4-into-1 1 7/8" long primaries into twin 3" system), so maybe I'll "suck it & see"!
Chris