Rebuilt Slant 6 but No Spark help!

At this point, I would remove the distributor so you can spin it by hand to test. You don't want to run down your battery and starter just to check the ignition. Since a new rebuild, when you do crank the engine you want to get it started fast and running at >2000 rpm to break-in the new camshaft and lifters (before they can wear a groove, i.e. "wipe the cam"). Also, it isn't easy fooling w/ points in a slant distributor down in the dark grub zone.

To test, run a jumper from the case of the distributor to BATT-. Connect a spark plug (or tester) on the "coil HV wire", with the electrode of the plug grounded. When you spin the distributor shaft, you should see a spark each time the points open. Don't leave the points closed very long while the coil+ is powered or you can overheat the coil and points so try to stop w/ the points open. When closed, they are charging the coil's magnetic field, which only takes a few milliseconds. Break that current and the magnetic field collapses and forces current across the spark gap, building up whatever voltage is required to do so (up to 40,000 V, but less is needed in 1 atm air). Adjusting the points gap determines the coil charging time, known as "dwell angle". You get it close w/ feeler gages, then tweak with the engine running using a "dwell meter". This is all an ancient skill-set. When you tire, convert to electronic ignition where dwell time is designed-in (at least in HEI modules) and let the engineers worry about the details.