I did this conversion in 2002 and have been using a electric pump from a RX-7 non injected car. Have never had any issues with vapor lock or any problem for that matter. I eliminated the mechanical pump, they act like a heat sink, and block off the opening. I have since changed engines to a F-54 with a P-79 head with cam and headers. No heat shield other that factory and again no problems. I used a simple tee into the block much smaller than the one pictured , attached the pressure switch to the side opening and the sending unit on the other. Looking at the area you cannot even see any difference from stock. I simply ran a couple of wires fron the pressure switch , right to the green wire comming from the pump on the passenger side . Cut the wire and connectec my new wires in line. This power sorce is fuesed , factory, with a inline 20 amp fuse between my splice and the power sorce. I can see no need for a relay, The pressure switch I use closes when the oil pressure reaches 7 psi. then the pump is activated. If you ever run out of gas, simply use a modern fuze with two male spade connecters , un plug your wires and bridge them with the fuze . Turn the key and fill the float bowls. I have had to do this only once. Even after winter there is enough gas in the carbs to start the engine. But if not I use the fuze. This makes it a simple and clean uncomplicated modificaton. Just take your oil sending unit with you to your parts store , tell the counter guy what you want to do so you will be buying the correct threded parts. This is about a $10.00 conversion . The RX pump is quiet too. $15.00 at the local u-pull-it. they make 4 1/2 psi. I cecked wtin ztherapy when I did this and Steve told me the limit pressure is 5 psi. Hope this is helpful. All the best. Gary