There is a guy in NY with an LS1 in a 57 Chevy- really sweet car, can drive it anywhere too

.
I personally love new power plants in old cars- you get the power, reliability, gas mileage and ease of tuning with the classic Muscle Car look!
As for superchargers making more on a traditional carb setup- no way- not with setups being equal. You do have the opportunity to go with a 12 71 or some other monster though- but they aren't the most effecient either. Other than that, put a P1 on a fuel injected LSx motor and on a stock 350 small block and see which one runs stronger

. Only thing the small block has over it (I just realized I am talking Chevy though, not pontiac

) is better head clamping at higher boost levels and easy parts accesss (though parts are everywhere for LSx's too now). The head design alone on the LSx is much, much better than a traditional small block head.
I've had them all- muscle cars, late models, Fords, Chevy, Mopar (I wish I still had my 71 Cuda 340 Convertable

), Imoprts, etc. and out of all of them, the best bang for the buck comes from the LSx motors and the 4G63 Mitsubishi 2.0 Turbo. They both respond ridiculously well to mods with the 4G having better response with less parts needing to be changed. I dunno, I guess that is just where my experience has left me.
Joe