66 Valiant Electrical Issue?

No here's what you do with the lamp

UNHOOK the battery ground cable from the block, and if there's a separate (small) ground pigtail to the body, unhook that. You should now have a ground cable hooked to the battery, with the end in your hand, and NO ground to the body or block

Now hook up (jumper) the fuse link

Next, hook your lamp I mentioned to ground, preferable to the body at this point

Hook the other terminal of the lamp to the ring terminal of the unhooked ground cable. Now if you have a short, all that happens is the lamp lights!!!