Ok, so I put it all back together, along with a RV crawler cam from Engn Builders.
The poor old thing (300+k original, 100+k on last full rebuild) just seems to gently cough or miss a little bit at all revs, just enuf to be annoying, whether you advance or retard the ignition timing. Runs smoothest at idle, starts right up with no trouble every time.


1) made double-d**n sure that the chain marks and sprocket marks were ON!
2) Adjusted valves not once but twice.
3) Compression check showed range from 135 to 145, with cheezy old walmart gauge.
4) plug wires are good
5) sprayed both WD and carb cleaner along intake manifold flange, no change, no leaks?

My neighborhood savant who solves most of my issues, upon giving it a brief listen concludes that: It's either a carburetor issue (I can live with that, it's an ancient Aisin), or (shudder) the machine shop did a not-so-great job with the valves. Neighbor savant-guy has always had a pessimistic streak.

Funny thing is that before this work, other than the horrendous rat a tat tat of valves stems being pounded to death, the thing ran pretty evenly, ancient Aisin notwithstanding.

What gives? I gotta drive from Taos to the east coast in a day or so, and don't wanna go down in flames by the side of the interstate, so any timely suggestions would be MUCH appreciated!

...And many thanks to Justin for shipping me that head!!