There is another option that's not been discussed here. I'm intending to try it on the LS-swapped truck in my signature, but I don't have it functional yet.
Each side of the truck will have a 1987 tank, 1987 sender, ep381 pump, and a Corvette filter/regulator. The two outlets from the regulators will be teed together using a shuttle valve, and sent on to the fuel rail.
The shuttle valve is the critical part here. It's basically a double-inlet single-outlet check valve with a single check ball. At first glance, you'd think you could use two check valves and a wye fitting to accomplish the same thing, but this is not recommended. The double check valves means there's no way for expanding fuel in the rail to make it back to either tank. If you're using a shuttle valve, any heat-soaked fuel can get back to one or the other of the two tanks while the engine is off. I've heard of folks using the double check valve and Wye fitting idea, and they report problems with hot starts. The truck won't start while hot until they bleed some fuel out of the rail.
I'll have two fuel pump relays, with each relay controlling one pump. A double-pole double-throw switch will be installed in place of the regular tank switch. This will switch the fuel gauge between the two senders, and will switch the ECM pump signal between the two relays. Everything will be redundant except for the switch and the ECM. Any other single part can fail, and half the system will still work fine.
I'm planning to use this 1/4" shuttle valve. Based on the flow factor, and some calculations, I'll be fine. But I do wish it was a little bigger, though. I couldn't easily find a 3/8" shuttle valve like I would have liked.
http://www.pneutrolspares.com/media/...atasheet_1.pdf