Ken, I know you do a ton of research when you do your builds, so again I am going to try to save you some time by helping out and hoping you have not already done this research.
Previously I mentioned the fuel pump pressure depending on what EFI swap you plan for in the future. The same principle applies to the Fuel Tank Selector Valve. The stock C10 valve is a low pressure rated valve and would work for a TBI system, but not a system requiring more than 20-25 psi of fuel pressure.
Pollak makes a high pressure tank selector valve that works with the high efi pressure requirements. Here is a good refence thread for the dual tanks for use with EFI...
http://67-72chevytrucks.com/vboard/s...d.php?t=379708
I am planning a LS swap into Owen's '84 this summer and the intent is to use the dual tanks and have it function as is should stock. At this point, I am leaning to use Jabin Wood's (gmachinz) harness kit he makes for just this type of swap (posts #17 & #18 of the above thread)