1972 Demon 340 engine mods

OK, well you can put one of the standard single section ballasts in place of the lower half of your dual ballast, and then keep the upper half connected. Good on having some access to spares. And very good on the meter lead resistance being 0.0. That means that lower ballast half is definitely not right.

And OK on the plug wires being hard... that is not a good sign for them. They sound like they are shot.

By the way, you can check the coil primary resistance too. The coil + to coil - is typically around 1.4 or 1.5 ohms for a stock type coil.

And I cannot remember: Have you measured compression on all 8 cylinders?