Barb, I believe the motor that came in the car was throttle body injection, is that correct? Are you changing over to a mechanical pump because you now want to run a carburetor and the in-tank pump produces too much pressure for the carburetor? If this is the case, have you thought about using a regulator with the in-tank pump to bring pressure down from the 12-15 required by the TBI to the 5-6 psi required for a carburetor? You could keep the entire system in place and just add a regulator, I think.
http://www.summitracing.com/parts/MAA-4309/

P.S. Most mechanical fuel pumps will produce excessive pressure anyway. If you run too much pressure to the bowl, the pressure will overpower the needle and seat and blow raw gasoline into the intake manifold, presenting a tuning nightmare. Here is one that produces the proper pressure so that you don't have to use a regulator....
http://www.summitracing.com/parts/CRT-M6624/