Doug,

How were you going to bump the engine? Don't do it from the ignition switch. Use a jumper wire from the positive terminal of the battery to the purple wire on the starter solenoid. Your SD may have a terminal block on the fender well close to the turbo. You'll see the purple wire there (it's the first wire closest to the fire wall on my 81SD).

With the key off the injection pump is not enabled and the engine will not start...jump it for an extended period of time just to see...it won't start.

What makes it really easy, is if you make up a little remote bumper switch. I took an old push button switch and connected two five foot long #12 supple wires to it and soldered an alligator clip on one wire and a small clamp like you would find on a little battery charger to the other wire. This way when your bumping, you can concentrate on looking at lobes and not at the electrical connections. And then some day you can drop it down under the car and bump it while looking for the torque converter drain plug while servicing the trannie.

Take your time, follow the book and every thing will turn out just fine.

Good luck
Ernie