Here's a couple of links that will might give you a few ideas on the fuel pump thing....
Page 4 of this article is about an external fuel pump setup on a '66 Mustang EFI Mustangs Plus - Tech Articles - Project EFI GT (Page 1)
Tanks, Inc has a '64-68 Mustang fuel tank for EFI already setup for internal pump. This is the one I put on my truck.1964-68 Ford Mustang Fuel Injection Tank
And here are instructions on how to cut a hole and mount an internal pump yourself. It might be kinda scary on an old tank but.....;)In-Tank Pump Installation