Roger on the gauges; I suspect you are spot on. It's just to avoid any teardowns if possible.
All the above ideas are on the table if the cranking pressure is still up there in the 180ish range. In order of effort and cost:
1. Thick head gasket: Think Cometic. If it were the case that you had 65 cc chambers with a .028" thick head gasket, you would have to go to around .065" or .070" thick to get the SCR to 9.5 or a bit less, and the DCR to 7.9-8.0. If the chambers are smaller, then the gasket needs to be thicker. I have no idea just how thick you can go, and if there is any risk in blowouts, but Cometic makes them well over .100" thick. You can always put in ARP heads studs and clamp the heads down harder. (Keep an eye on the rocker oiling path in the head bolt hole with ARP studs.)
2. Cam change for a later intake valve closing from some combination of :
- Wider duration
- Wider LSA
- Less advanced cam timing
This is gonna change the engines personality more than the compression drop, so if you picked the cam for a particular purpose, then perhaps this is the last thing to consider.
3. AL heads: Maybe look at the Edelbrock 63 cc ones (closed chamber) and Cometic head gaskets around .055", or the 65 cc 'open chamber' versions, with the 8553PT head gaskets. Either will put your SCR in the 10.0ish range, and DCR in the 8.4-8.5 range.
The AL heads are the costliest solution but also keep the SCR up higher to help maintain the crisp low RPM torque you have now. And the breathing will be great and will help performance across the board. Do you have the stock rockers right now?
