if you go to blowthrough with a supercharger, there is one more option (instead of a throttle plate connected before the supercharger inlet, so that it closes when your carby throttle plate closes ) - and that is to have the second throttle plate (or even a pop-off valve) on the supercharger outlet, connected in 'reverse' so it only closes when your carb throttle opens. That way, at part throttle, it will vent off the excess air that has come through the supercharger, so the carb won't see pressurised air. If you don't use a second linked throttle a pop-off valve (more or less just a regular turbo style blow off valve) will do as well (some would argue even better). AFAIK the aftermarket supercharger kits for blowthrough carb setups on 'dinosaur' v8s all use such an arrangement.

The one difference this would make is that at part throttle the supercharger can still be fully engaged, but it won't be compresing any air, as it's just flowing through and then out the bov/vent. This constant stream of air through the charger (and no boost - remember compressing teh air also creates heat) keeps it cooler, and it ought to last a little bit longer (possibly).

FWIW, you'll tend to get to the point of the limit of the supercharger rpms/boost level, where it will risk the supercharger self destructing, relatively early in the game, compared to some aftermarket blowers. Which means you could (for simplicity sake) just run a drawthrough carb setup, without the intercooler, and run water injection, and you'll be at the limits of the supercharger before you reach the limits of the amount of boost you can run without detonation (well at least as long as you are using water injection). In this case the drawthrough option and the water injection aren't technically superior in any sense, it's more a case of they are typically a lot easier to get working for a first adventure with forced induction.

Having said all that, the price of efi computers (and you certainly don't need the most expensive one or anything like it) has come down so much, and you have a manifold/fuel system (or teh beginning of one) already, it'd be hard to argue against its use.

On the supercharger you have - in their original factory fitment, there was a bypass valve that would let air travel from the intake pipe on the supercharger, through a pipe all the way around the s/charger and plumbed back into the supercharger outlet pipe. That way, when the supercharger wasn't spinning, all teh air the engine requires would flow around this 'detour' and none would need to try and get through the supercharger. The supercharger itself was switched off most of the time.