I use a cheap 4-inch 3-jaw puller. I have to disassemble the puller in order to get it where it needs to be, i.e. I put the legs into the holes in the gear and then bolt the puller together with the legs already in place, due to size constraints on the holes. But it doesn't take a particularly special or strong puller. Main thing you're looking for is versatility, so get one that can be taken apart and put together a couple different ways and you're sure to find a way that works.

The nut is 36mm. The gear-to-cam fit is not tapered. Just pulls straight off. Orientation is done by a woodruff key.

A small spacer ring provides the clearance for the thrust plate; symptoms of a missing one are quite spectacular indeed. When I was a foolish young lad I left it out once and about 800 miles later the cam gear nut crashed right on through the timing cover. I've got the photos to prove it. Anyway, let's hope he didn't leave out the spacer.

Availability on thrust plates is sporadic and if you're suspicious it may be worth your while to buy one ahead of time.

Before you remove the timing gear, check it for backlash. Turn the crank forward and backward a bit, and see that the gear turns immediately in both directions with no obvious gap between the gears.

If it's not clear that your rebuilder used a new timing gear in his rebuild, just replace the darn thing. It's a well-known wear item on these engines, and the symptoms of a worn timing gear can be absolutely perplexing. I once had one that caused my distributor rotor to pop off at random intervals. Try troubleshooting that! But sure enough, it turned out there was enough lash in that gear to allow the cam to vibrate in just such a way...

And if your rebuilder did not use a brand-new timing gear, be sure to give him a poke in the nose. Why, oh why, would he think that part is re-usable?