No power to fuel pump

Me and my grandpa bought this truck and got it running good and had the stock 305 in it. But that blew up so we did a motor swap which is a 350 from the 1970's. But the guy we got it from said it was an 1986. We got the motor in and hooked everything up, some plugs from the air pump and cruise control not there because we didn’t put that back on. We changed the fuel tank because it was leaking. And when we went and tried to start it there wasn’t fuel. You could spray it with ether and it will start. There isn’t power to the relay or the pump but pump works fine we tested it. And the ECMB fuse on the fuse panel blows every time you turn the key on. We can hook a jumper from the tan and white port on the plug that goes in the fuel relay and try to start it then there is fuel coming out of the injectors in squirts like it suppose to. But still doesn’t start which I think is cause it has smaller injectors. Any help would be greatly appreciated.