1/4 mile times

To get the best compression readings, you need to do these things.

Get engine to (or close) to operating temp.
Pull ALL spark plugs
Open throttle all the way & tie it off, with it being a vacuum sec. carb, the rear butterflies will not open with the engine off, you need to figure a way off tying them open too.
Make sure the battery is at full charge, or strap a trickle charger to it while running the test.
Use a romote starter switch hooked to the starter relay.
Crank engine, run 4-5 strokes on the guage, your 1st. comp. stroke will read the highest, take note of this reading as your running through the strokes.