From what my engine recond guy told me for my supercharged engine on a standard cam, between 7.3 to 7.8 /1 and with boost ground cam I could go higher to 7.8 to 8.3 /1.....so I would say dont go any higher....

Up it to 10 and run E85, have a bit of fun with it. Run moderate boost until you're confident you can wind it up.

Or play it safe and stick to 8? I have a selection of decompression shims that can be used to experiment with.

You can use a supercharger on a stock A12 -- 9.0 compression.

I tuned the carby on my turbo setup myself - via on road testing and a WBO2.

Idles at 14.7:1 and tapers down to 12.5:1 at peak torque (ie max cylinder pressure) then revs out to 13.5:1 so this is almost ideal for a turboed car's fuel air curve. Alas the problem now lies in that this is good for power but unlike EFI the carby wont lean out under a low load situation...meh - she's not a daily.

Also because I'm not using ur typical SU my carbie flat slide is mechanically opened so just pulling out from a dead stop if you just flatten the pedal the car picks up until the accelerator pump shot burns off and because the enigne RPM isnt enough to suck fuel its self at that point it leans outs. This isnt a issue because If you were to launch the car you would do it in boost and crusing wise you dont open the throttle that fast - anyway, the pump shot would need to be 4 seconds long to over come that and would kill the engine when heel toe downshifting. However on road its awesome. Fuel air ratios are great - because I machined my own carbie needle, jets and emulsion tubes (cant buy the right ones to get the fuel air needled for a 1.2L turbo motor to be spot on).