Need info on a return line back to the fuel tank

[streetmaster42]

Need some advice on putting a return line on the fuel system. The 76 GMC had an I6 in it, and it only had just 2 lines coming out of the fuel tank when i tore my truck down, i guess one of them was a return line, not real sure about that one. I've always thought that it went to the charcoal canister, its only been 10 yrs since i tore this thing down LOL. I replaced the I6, with a 350 sbc, and it has 110gph Holley mech pump on it. Im putting the stock tank back on soon, and im not sure if i need a return line with my set up or not. Since i replaced the I6 with a 350sbc, should i then replace the 2 line fuel pump, with a 3 line fuel pump, im not really up on all this fuel system stuff. (Please Advise)