I ran a SC12 setup like you're trying to do for over 5 years. Stock 9.4:1 seven-rib largeport from a FWD FX16. The stock N/A ECU will not "just work". You will need bigger injectors to give the engine enough fuel to match the extra air getting forced in by the SC. You might could find an injector that works OK in boost but then you'll have too much fuel at idle and possibly wash down your cylinder walls with fuel. Stock ECUs are setup for a specific injector size so if you replace that with a bigger injector, the stock ECU isn't going to know to not hold the injector open for so long. This is why you need an ECU setup for what you're trying to do, either a real-deal GZE ECU with matching harness or a programmable ECU. You should be able to piggyback the MAP GZE setups but if it's a US GZE ECU it might not work with a SAFC for the same reasons the US AE86 flap door AFM ECU won't work, incompatible air meter voltages.
To run a GZE ECU you'll need a GZE harness from the same year / model ECU to be sure the pinout is the same between the harness and the ECU. The GZE ECU pinout or connector won't match the AE86 ECU connector or pinout so you won't be able to just get a GZE ECU.
I ran a MegaSquirt on my SC setup and re-used the stock N/A harness. I made an adapter to go between the MS and the stock connector plugs and had to run a few more wires for the SC clutch, etc.. that's not in the N/A harness.

I ran the engine hard for over 5 years, drift events, etc... The cast pistons can absolutely go at any time but I had mine tuned on the dyno, paid attention to AFRs and ignition timing, and never had an issue at 8 PSI. The engine is still in the car and running great but I've sold all my SC stuff in the past year or two and have an ITB setup now.
How much of a "bolt on" the SC stuff is will be determined by how much of the complete setup you have. If you're missing SC specific water lines, SC specific water outlets for the head, any accessory mounts for the SC, PS, alternator, etc.. then it will be a bit more work to either find what you need or make what you need. When I did mine since the SC goes where the ALT normally is, I ditched power steering for manual and the dealership still sold the US AW11 GZE alternator mount that puts it right by the distributor (PS pump location). I don't know if they still sell it or what the part number is but the dealer should be able to look it up and see pretty easy. I was missing the SC water lines and water outlets so I had to space the whole SC off the engine 1" to clear all the N/A stuff between the supercharger and the block, mostly the water outlet at the front of the head I was using I think. There are also going to be things you'll run into that will need figuring out on the spot and possibly requiring a trip to the hardware store, like since the TVIS plate doesn't get re-used you'll need shorter studs / bolts to mount the GZE intake manifold straight to the head is the best example I can remember.