Raising Compression or Throttle Bodies?


So as a next mod, I am stuck between:

1. Raising compression - can't find enough info on raising compression on a CGA3. I am thinking to leave the stock pistons but just skim the head, how much should I realistically be looking at skimming and what sort of power gain could I expect? (its on a stock CGA3 exhaust cam and a 250deg 9mm inlet cam). I have also read that Ferriday Engineering can make a CGA3 head gasket of any thickness, so would a thinner head gasket be a better option as I don't want to introduce any slack into the timing chain?

2. Suzuki GSX600R throttle bodies - looking to get these fitted along with their corresponding injectors, with the plan being to route the air through the GSX600R airbox, with an MAF mounted into it for all 4 throttle bodies, so that I can use the stock ECU to run these. What sort of gain could I expect on these?

What is the general consensus of which mod would be more worthwhile to do first?

Thanks for any advice.