Tested my starter (battery cables and large screwdriver) and its hit or miss.
It spins, but doesn't always slide over, sometimes it would slide over and slide right back and other times it would slide over and stay there. Sometimes it wouldn't slid at all. I just went ahead and ordered a new starter. But so I understand how a starter works should the pinion gear slide over and stay there until the car starts?
Distributorguy is Jeff Schlemmer and runs a shop in MN called Advanced Distributors. He is very knowledgeable.
Re-curving a distributor is actually very easy, but you need to know what to modify. Unless you've done one before, I would leave it to a pro.
We used to call that an engine douche. But we used substantially more water. A small stream from a garden hose at about 4000 rpms is how we did it back then.
There has to be a vacuum hose diagram somewhere. I just googled Datsun 720 vacuum diagram and came up with some promising results. Note that there are always a few iterations of vacuum hose routing on a given vehicle, which usually correspond the which part of the world the vehicle was originally sold.