Stubborn starting question...

The camshaft timing skipping a tooth is a good suggestion. However, most here would say that would cause a permanent problem, not the erratic "no start" condition experienced. You can easily test for slop in the chain by turning the crankshaft by hand forward, then reversed and see how much "lost motion" in the distributor rotor. Many posts here detail that. If <5 deg slop, unlikely it could have skipped, but who knows if your engine has the nylon cam sprocket since might have lost some teeth.

I am confused by the 1600 rpm idle and the timing light measurements. Your engine would be "racing" and would kick hard when put in drive. I wonder if the idle (600 rpm) timing is way too retarded (after TDC). Forget the manual specs. Most people find their car runs better with much more initial timing, say 15 deg BTDC at least. Some racers even go further, since they don't care much about idle anyway.

If it only runs well at high rpm, you likely have a vacuum leak, but could be a bad distributor (check "centrifugal advance" works), or a timing chain that skipped a tooth (runs better at higher rpm, drag racers do that on purpose).