i have an 1987 350 tpi. i was just wanting to if the fuel pump in the tank quits can i put an aftermarket fuel pump on with out taking the old pump out of the tank. what i want to do is run the it through the old pump so i dont have to drop the tank

 

Walbro has some nice intake pumps, and for the most part I believe they're cheaper than externals, an extrnal pump already has a harder job than an internal, and to suck through another pump probably just makes things worse, keep your mind open to replacing the intake pump.