2500A (574) won't stay running

Have you checked the fire from that coil wire? Since your dad used the choke to coax the tractor home, I thought it was a fuel problem. Place you hand over the throat of the carburetor while someone makes an attempt to start the tractor. There should be good suction on your hand. This is how we used to check cars and trucks when we suspected a faulty fuel pump when they used mechanical fuel pumps. Since this happened all of a sudden I would bring No1 piston to TDC on the compression stroke. You need to pull the sparkplug near the radiator and hold your thumb over the plug hole while someone hand cranks the engine until you feel compression against your thumb. Then look for your timing mark and keep having the engine cranked until the timing mark is aligned with the pointer. Then pull the distributor cap and see where the rotor is pointing. It should be at the No1 plug tower. Hal