The issue with "draining" to one side is that you could potentially lose coverage of the pickup in an off camber situation or going around a turn. A baffled sump would better retain some amount of fuel so that the pickup would be less likely to "starve" for fuel.
At a basic level you're going to need a filler neck (with breather), pickup, sending unit, and some way to mount the tank (most applications use tab or straps). Depending on your engine, you may need a return line if it is fuel injected.
Check out the aftermarket tanks and fuel cells to see how things are basically done. They typically have openings with gaskets to connect the sending unit and pickup - and possibly for the filler neck depending on the configuration. Returns are often done with AN fittings.
I hadn't considered the issue of moving from side to side...
Thanks why I ask so many questions,.. usually someone can tell you things you had not thought about.
I'll have to check into a sump.
Also,... Would this be something I could just cut a two or three inch (around) and about a one in deep hole in the bottom of the tank, and pit the bottom of the pickup in that. (I'm on disability and fixed income, so trying to save everywhere I can)
I had planned on putting a breather on the tank itself, so I suppose that would work also; and not need the breather on the filler neck.
I have the sending unit already, and have things figured out for mounting.
I'm going old school and not using EFI. Carb will be on the motor. I always figured I'd need a return line,.. glad you mentioned I didn't need one with a carb. (also one less hole to drill and a place that could leak - and fittings, and more fuel line, etc)
I am building my take with a recess something similar to this. I had planned on putting all the items here. (I'll try to attach photo???)
I figured I'd have more space to tuck the tank a little closer to the bottom of the bed
http://s158.photobucket.com/user/pickupguy07/media/tank_zps974f8251.jpg.html?sort=3&o=0
(well that didn't work. But the link should show it..)
Thanks for your help so far...
Anything else is much appreciated