Time to rebuild?

his mech who did the leakdown test heard hissing at the tailpipe and at the carburetor (=valves aren't sealing, either).

Yeah, I forgot to mention that important tidbit in the original post. I always forget to mention something.

Truth be told, I'm kind of excited about doing a rebuild. I didn't buy this car to be maintenance-free and reliable--I have a Mazda for that. And as Sean points out, a rebuild could be one of the best experiences I ever have with my son before he's gone into his own life (cue Harry Chapin). I guess I'll order the Boxwrench video on engine rebuilds, crack open the FSM, and turn this into a (re)build thread.

--Rich