Okay, here's my progress so far:
Here's Hoss as it came from my friend Jeff Morris:
First step: remove a little wood and fit the Musicmaster Bass neck to the body:
Next, I measured and, howsabout that for good fortune, the bridge goes right where that ugly spot was (glue from something Jeff had affixed to the guitar). I then cut the pickguard to fit and put it on, too (not easy to get that nice little curve, darn it!):
So here we are as of tonight! I now need to enlarge and reshape the hole for the pickup (I'm putting in a GFS Music Man copy humbucker, and it's HUGE!). Not sure just what to do about the six string holes from Hoss's earlier life as a guitar, probably just ignore them or maybe cover them with something decorative...
Tim