Ok - FINALLY tackled the fuel weep... was not really fun.
Just happened to run across an in-line valve at Trophy Cycles in El Cajon (awesome place, BTW).
Cut that baby in half and tigged her in:
The nipples tigged in reallllly easily and the welds looked nice!
I cut out the old brass nipples and tigged a plate over where they used to be. This was less easy, and the welds did not look nice - I ground them down a little.
The tank held water OK, so I put it all back together and had some leaks in both weld areas...
Pulled it all apart and it took a few tries to get it right, but I eventually got there. Doesn't look very nice, but I'm very happy to have finished it.
Best of all, I rearranged the way the aux tank sits so that the fuel line is no longer vulnerable in case of a crash.
I think the bike's good to go now - nothing really left that doesn't sit well with me. Maybe one day I'll dyno her, get a couple more ponies in there somewhere.