Part of the reason for the three panel back was to be able to use up all the smaller pieces of Rosewood they had.No key crack, just the one near the pickguard/bridge. Neck is fairly straight with a slight angle, but I am not actually sure I am measuring the angle correctly. Saddle is a bit high and has room to lower but is stuck in place - not gonna try to free it.
After a string change, I am happy to report that harmonic intonation is dead on across all 6 strings - I let out a sigh of relief. So I am inclined to believe that this one has correct bridge placement or it had been corrected at some point in its life.
I am leaning towards "keeper" at this point - I've had a cracked top repaired before and well, Dierks Bently and Willie Nelson have holes in their Martins, so not too worried.
I'll have the saddle adjusted/replaced at some point in the future and just live with the slightly high action for now.
Really, I thought they had stopped doing that in late 60s / early 70s. I figured a '76 wouldn't have had that available at that point in time. Cool to know - thanks!