Low compression doesn't mean bad rings - poorly adjusted valves, valve job needed, head gasket leaking... all sorts of other 'normal' potential causes for lower compression.
To really nail it down you need to do a leak-down test. Basically you're putting compressed air into the cylinder via the spark plug (like a reverse compression test) and seeing where the air leaks out when at TDC.
If it leaks out the open oil-filler, or in the SR's case, out the hole where the oil hose connects to the engine case or drain hole, then it's rings (air goes past the rings, into the engine case and out the hole)
If it leaks out the carb, it's intake valves
If it leaks out the exhaust, it's exhaust valves
If it leaks out the head gasket... well, you get the idea
Much more definitive test. I got myself a Snap-On leakdown tester a while back on eBay for $40 but honestly haven't had a reason to use it yet, so I'm no expert, but if you're chasing compression issues and don't necessarily want to rebuild the engine, then it's a good place to start.
I'd check the 'mechanical' things first of course. Timing, valve adjustments to start, to make sure everything is where it is supposed to be at TDC. At 110 PSI the engine should run fine.
