how to tell if the distributor drive gear is installed correctly?

The facts are these, and we've joked about this. One member used to say, "the gear could point to China." You COULD do this:

1 Throw the gear in any old way

2 Throw the dist in either way

3 Pull no1 plug. Stick your finger in, bump the engine to find compression. When you JUST STAT to feel compression, STOP and look for the marks. Wrench or bump the engine NOT TO TDC but rather WHERE YOU WANT timing AKA maybe 12-15BTC.

4 Now, if you have points, rotate the dist body CW (retard for a SB) and then back again slowly (advanced) until the points open, or if you have breakerless, visually center the reluctor in the pickup coil

5 NOW look at where the rotor is. Plug the no1 wire into the tower which the rotor is JUST approaching, plug in the rest of the wires re: no1 and START IT UP

I am NOT saying you should do that, as the plug wires won't lay correctly necessarily, and the vacuum advance might not be "in the clear" but the timing WILL be right and it WILL run, assuming no other problems