since i've gotten my engine back in the car, i've got no electrical power at all. no lights, no reaction to turning the key, et cetera. the battery seems to be fully charged, and i was very careful to reattach everything just as it was before the rebuild. i've replaced the starter unit and the fusible links, but that's all i've changed. if there's one thing i'm absolute pants at, it's electrical stuff. where should i even start looking? is this being caused by a short, possibly?

You have a bad fusible link

It's something to do with the main supply. Either a fusible link is bad, as Manny suggests, or you didn't connect the wire feeding the fusible links to the + post of the battery. It probably connects in alongside the cable running to the starter. You might also have a wire that connects to the + post of the starter. In fact I think I had both in my '78 before I reconfigured it.

ok, it was a fusible link. all fixed now, thankyou now i've got a new problem! i'll post it in a new thread