Fuel Tank Selection

[djbnola]

Looking for direction in selecting the right fuel tank for '48 3600 pickup. Would like to mount tank in original location under bed w/original filler neck location in front of bed passenger side. OEM replacement is no longer available except for 1/2 ton under bed (not sure of fit) and inside cab w/filler neck relocation.
I would like to find a tank that will serve the original 6 cyl 217 mechanical FP now and also work later when I do an LS package upgrade with possible EFP or EFI.
Question 1: if I am able to find a tank that will fit in location, will an updated tank work with the original FP? (Original pickup port on front bottom of tank)
Question 2: if I use an original type tank, can it be reused safely when I do the LS upgrade? (Baffles, pressure, return line, vent, etc)
Question 3: Are there any possible issues that may be encountered with finding a sending unit that will be available and/or comparable between an updated tank and the OEM 6v wiring? Future problems with LS upgrade?
I appreciate any advice you can offer or direction to another thread.