EFI fuel pump, Stock tank.

If your magnum is making similar power to a stock magnum the cheapest alternative is to use a stock dodge truck pump from an obd2 system. You’ll need obd2 fuel rails also. The stock pump has a regulator built in to it so no return line needed. You can either buy a new stock tank or use your original one. If you use the original, take it out and fill it with water. Cut a big hole in the top, weld on a few studs, drop in the sending unit and away you go.