68 plymouth 273 question

You may have to consider adding an electric pump to keep things primed. Mopar action had a good tech article in solving this problem. Try checking their online tech archive. I don't have a link handy.

Just did a quick check on my phone, can't find the article I mentioned. I do recall Ehrenberg adding a 1/4" return line to the tank to keep a continuous supply of cool fuel to the engine.