In my mind, "would not crank" means that the starter is not turning the engine over. Is this what you meant? Or, was the engine turning over, but it was not firing? If the engine wasn't turning over, you could have a defective starter where some of the soldered connections on the armature are bad and there are dead spots on the commutator. If the starter happens to come to rest on one of these dead spots, it won't turn when the starter switch is engaged. But if it comes to rest on a good segment of the commutator, it will work. If you meant it wouldn't fire, I would still look at the ignition switch or wire connecting the lower plate to the points.
How long did it run before he backed it out of the garage? Long enough for everything to really heat up, or just a short while? When it stalls, does it pop and backfire and run poorly for a little while before it dies, or does it just stop dead like you've turned the key off? If it stops dead, my vote is a bad ignition switch. Even new switches can be bad. If it runs poorly before dying, I'd look for a short in the distributor.
Another thing to look at is fuses. Do you have a fuse in your wiring? A fuse holder with loose connections can cause intermittent electrical problems like you're seeing. The fuse holders that attach to the starter motor have been known to corrode on the underside making bad connections.