Is there a way to test just the clock prior to installing it without having it connected to the PCB? It only has a single terminal on the back.

Thanks

Run a 12V wire to the terminal and a ground wire to the case.

I would get your clock converted to Quartz Why? I did a frame off on my one owner 70 SS 454 M-22. I sent my clock out and had it rebuilt to factory specs $90.00. Did not want quartz. 4 years later the clock quit running. I am not going to pull the dash apart again. If I were you I would consider quartz. 70-72 clocks have a motor that winds up the spring, Then the clock runs on the spring unwinding. After the spring unwinds a set of points close and the motor winds the spring again. What kills old 70-72 clocks is this. When your car sets and the batt. gets weak and voltage drops the points will stick and the clock motor cooks due to lack of of voltage. The only visual difference in movements a quartz movement you can see the second hand jump each second VS smooth rotation of the old style spring movement. Cost for rebuild is a bout the same.
Ask youself how many times has the points opened and closed in 30-35 years, And do you want to remove the clock in the future. I should have went to Quartz. Also with a quick disconect on batt. If you catch the clock in a certain spot in its cycle you will weld the points I think thats what I did. Bob ACES-AACA

I installed a hidden switch under the dash and turn off the power to my clock unless it is going to be judged. Still going strong.