Fuel pumps

[Security guy]

Educate me! I've got a '71 1/2 ton with a 402 thats not original to the truck. I got a replacement fuel pump for a 402 and its got the extra port for a return line. My gas tank don't have a place for a return line so I assume its been changed to a '72 (I think). Can I get a fuel pump without the return line? The problem is that this motor was in my dads truck and he never could get it to run because it kept filling the crankcase with gas. He had the return line blocked off. Are these pumps 'high volume' that it requires a return line? Is the pumps without a return line a lower pressure than the pumps with a return line? I'm trying to find out if its cheaper to find a pump without a return line, or try to drill a hole in the tank to add a fitting for a return line. I've also thought about putting a 'tee' in the feed line but that might cause some problems. Anybody know about this?