Custom fuel tank questions

[jetfixr]

Well my truck has been rusting away in my driveway long enough. I decided to jump back into it with the goal of first making it a daily driver, and doing week-end project. At some time later I will be looking at a LS1 swap. I decided my first project would be to get the tank out of the cab. I really don't care for how low the blazer tanks hang beneath the frame. Brothers has one that is tapered and so does no-limits. If I do an LS1 swap at a later time I would want a tank that is compatible for injection but would allow me to run with my carb in the meantime. I not sure of the type of fuel line fittings I would need to have welded into the tank to make this work? I am thinking I would need two, a supply line and a return line for when I actually go fuel injected? I guess I could just put a threaded plug in the return line for now. What diameter should the fittings be? Not sure if I should go with an in-tank electric fuel pump now and just have it regulated down for carb mode. Is there any drawbacks to going with an in-tank fuel pump? My main fear with this type of setup is that the fuel pump may become obsolete in the future and I would be replacing the tank because I could not find the proper size pump.