I'm not sure I fully understand the question.
If you have a fuel pressure regulator that can regulate the pressure down, you can't really go wrong with the $85 Ford pump. At which point, why upgrade your fuel lines? The Ford pump is a 5/16th pump and supports around 400 horsepower.
On a standard fuel pressure regulator, you can typically run different size lines in and out. So a 5/16th line in, and a 3/8ths line out to the carb is fine. You will need to run a return line still, which can be either 3/8th or 5/16ths with the Ford pump.
