>>BUT both the rounded mark and the triangular

mark on the pulleys appear under the strobe to be well to the left of the

seam on the block ... maybe 15-20 degrees. If I rotate the distributor

clockwise, the marks appear to move back toward where they should be, but

before they get to the line, the engine stalls.<<

Time for me to come out of the closet on this one.  I have a similar problem
with my '85.  I suspect the distributor was installed incorrectly at some
point and I fully intend to fix it when I rebuild it sometime in the future.
In the mean time, to time my engine correctly I have to connect to the #3
plug instead of #1.

You might also want to do yourself a big favor and drop into Pep Boys, Auto
Zone, or Sears and get an inexpensive tach/dwell meter.  With one of these
you can set your idle where it needs to be since your timing and idle speed
both need to be close to right to set the other.

Chuck