Fuel Line Choice and size

I believe o.p. has the magnaflow already, we are just trying to make sure it works efficiently and has a long life. FDNY340, you might want to look into a fuel pump controller that regulates voltage to the pump, depending on demand. It will help with a long life for that bad boy pump.
And yes, he likely has a lot more pump than he needs. I have been high tens with a 150, high nines with a 250 Mallory (LOVE that pump, but today's price for it is insane!) and the 250 was more than it needed.