Rosso Pintura

Take some Dirko and after making sure the area where the washer will sit on the head is very clean, smear some Dirko with your fingertip around the stud, pushing a little into the space between the stud and hole. Put the washer over the stud. Take more Dirko and run some into the threads of the stud nut. Torque. Wipe excess with a paper towel for cleanliness points. Wont leak.
 

It's the 4". The 3" doesn't have trigger wheel holes. You can see in the picture that it is 4", so I don't know what the ID issue is.

You may have seen this in a previous discussion, but the number one failure point of the box is the bushing in the top cover. The oil level drops over time, and the bushing stops getting the lubrication it needs and wears heavily. Screwing in the center shaft makes the worm gear push the center shaft off center, wearing the bushing, causing more play. So, the only real fix is to replace the bushing and keep the oil level up. Unfortunately, that bushing was never available separately, and ZF stopped making parts for that box long ago. You could make the bushing, but it is not as simple as it sounds. There is a oiling channel/notch cut in it which makes for even more fun to make. You'll have to decide how much time and effort you want to put into it.

PSA: a cutoff switch goes between the positive pole of the battery and the starter. The other side of the switch also connects to the main “hot” of the fuse box. The switch is intended to be accessible to corner workers or emergency personnel to shut your car down in case you become incapacitated in an accident, not buried in the trunk or elsewhere hidden. To prevent back feeding from the alternator proving power to the ignition, you either need a switch that provides a break to the ignition which are the ones with spades on the rear between the two poles, or a diode installed in line, coming from the exciter wire of the alternator acting as a one way only path for power. For the rest of the world who want one just for the sake of removing the battery power from the system for reasons of your own, I guess you can put it wherever you want. 

If you don't have luck finding a rental/loaner, I can let you use my factory tool while I'm at my shop in Duarte by appointment. I'll give you the space to work and the use of whatever tools that you'll need to remove your cam (assuming that's your plan) but no, factory tools will not leave my shop.