or... find a 5.0L fox tank with the fuel pump stand in place. take the 2 tanks to any radiator shop. have them cut the Fox tank 6" square around the fuel pump stand. then right over the MII top vent hole, center the 6"x 6" graft, weld the Fox stand in and get all you need in one stop. OE stand with up to 300lph in tank pump (cooler, longer lasting), OE float that works with your gauge, and return line where it should be, not heating the return side forced into the tank somewhere. $100 labor tops.
I've tried the on-frame/inline pump set up, and for all but a stock 5.0L they heat up. If you live south or in humidity, cavitation & vapor lock are issues. Just my experience.
The OE MII tank is a decent size and add a V-8 Aux tank at the fuel neck in the quarter panel and you have plenty of cruise distance.
I've supported 550rwhp SEFI with the MII tank & fox stand. Add -AN adapters at the pump stand and an upgraded 1/2" stand/tower assembly and good to well over what our beloved MI chassis can handle...