I do get spark but can't seem to get her to turn over.
Something doesn't compute with that statement. Are you saying the starter won't crank the engine, or that it's cranking, but won't start? Just changing the battery over to 12 volts won't be sufficient- - - -you need to upgrade to a 12 volt coil, and install a resistor in the circuit between the ignition switch and the coil to prevent the points from burning in a short time. Running a 6 volt starter on 12 volts is OK, but don't spend a lot of time cranking or you'll overheat the starter.
If the engine is cranking, the plugs are firing, it's got good compression, and it still won't start and run, you've got a fuel supply problem or the ignition timing is wrong. The spark plug is supposed to fire as the piston approaches the top of each cylinder on the compression stroke. A quick way to check ignition timing is to pull the valve cover, watch the #6 cylinder valves, and roll the engine over by hand by turning the fan (clockwise from the front) until the exhaust valve opens, then begins to close. Keep turning. The intake valve (2nd. from the rear) will begin to open. At that point, the distributor rotor should be pointing toward the #1 cylinder plug wire. (Not #6!) Once you establish that the rotor is pointing toward #1 at the proper time, the rest of the firing order should be 5-3-6-2-4, with the distributor turning in a clockwise direction.
Once the firing order and timing is sorted out, the only thing left is fuel. Dribble a little gasoline down ther carburetor throat (Don't overdo it!) and the engine should start and run a few revolutions. With a good gas supply and a carburetor in good shape, it should keep running. Good luck!
Jerry
