I have a 1990 Firebird Formula 305 TBI, and I was wondering how one of these electric superchargers would work for it?

 

It won't work in theory or in reality. Electric blowers are meant for yard work and not for cars. Also, they blow air at ambient pressure and do not produce boost (which is the whole purpose of forced induction). Take some time to use the search command for both electric blowers and for supercharging.