Let me see if I can boil this down into a new narrative. Carburetor percolation, which I have been mislabeling as "vapor lock" is not the main problem. The carb doesn't require any additional holes as it's already vented. While today's crappy gas and my high altitude location are not ideal, my other trucks, all with 235's and stock fuel systems, run fine. I've already installed another exhaust manifold, carb rebuild kit, glass bowl fuel filter, gas tank sending unit, and basic tune-up parts.
The main problem is lack of fuel at peak engine demand. The previous owner was probably trying to address this with a new fuel pump. The 57 runs fine when I'm not requiring much from it. Before I spend more time and money on new parts, re-plumbing fuel lines, or swapping around parts from other trucks, I need to start with a known-to-be-clean fuel tank. (Thank you, Otto, for your new vs. refurbished gas tank recommendation). I am planning on taking care of the dirty tank issue this winter. I might as well just drain the tank as drive the truck around the neighborhood for another 100 miles at low speeds to use up fuel.
Are there any other considerations that I've missed? Thanks for all of the feedback so far!
