71 c-10 LWB 305ci keeps dying

[triplejiib]

I am sorry this is so long but please help if you can.
Hello folks let me tell you my problem and I hope you can help me out. I'v got a 71 c-10 that came equipped with a 307 2 barrel carb with a 3 on the tree. The previous owner threw a couple of rods so the engine was replaced with a 305 TBI out of an 84-88 chevy (dont know the model). I ditched the TBI and put on a Weiand square bore intake for a 4 barrel as well as a quadrajet 4 barrel carb with the serial number 7041251 RC 2540. If I translated this right its for a 1971 49 state legal olds with a 455 and a manual trans. I can't remember exactly what web site I got that info from at this time sorry. Here is my problem, when my temp guage reads slightly over 180 degrees the truck will sometimes just die, and if I sustain 60mph the truck will act as though it is running out of fuel. I live in Tucson Az where the temp is frequently over 100degrees outside and the dying will only happen when the days temp has reached its peak. I have the stock radiator but replaced the thermostat with a 180 degree one ane I updated the origional 4 blade fan with a 6 blade fan.
My fuel setup is the previous mentioned intake and carb but there is a 1" aluminum spacer in between the two components. The 305 needs an electric fuel pump so I put on a Mr Gasket 35GPH pump. I was concerned that wasn't enough so I purchased a carter 75GPH electric fuel pump. After running the carter and still having the truck die I became concerned that the carter pump didnt have an internal regulator and might blow my needle and seat or something so I put the mr gasket back on until I can get the regulator and return line that is necessary for the carter (according to the tech support at carter). I am running the stock tank with an in-line filter. My thinking is that the carb is too big and might be sending too much fuel to the carb, and with the heat, possibly vapor locking. My next option was to buy a 600cfm edelbrock and loose the spacer at the same time then get the necessary components for the carter fuel pump. Oh and the quadrajet was professionaly rebuilt for a racing engine of my father-in-law but never used then stored in a bag in the original box on a shelf in a garage for 12 years then put on my truck with only the gaskets being replaced.
So if you have any ideas I would really appreciate them. I am on a very tight budget but any ideas would be great. Thanks