This chunker is looking very nice. As for the pulley, I don’t fix anything until it breaks. It looked like you had the motor and chunker flywheel lined up will enough that the pulley was running true and not trying to work it’s way off. The set screws are a good fix. You could also make a collar out of a piece of pipe and tap/thread a set screw through it to hold the collar/pulley on. Also, I would go for drilling/tapping the end of the motor shaft and putting a bolt with a large fender washer on the end.
For the wobble; yes it looks like a little much, bbuuttttt, I think when you cut the big section out for the actual blade, that you will not see that much motion. As you are standing in the position you will feed it from, the wobble left and right will not make much difference. The wobble in and out will be a problem though. When you cut the helical out, or what ever you want to call it, set the drum so it is in the position closest to you, and make the big step off in that area. You will ALWAYS be cutting in this area no matter how wide the stock is, and you want a good “cut” to finish off, so it breaks loose. If when you are done, you find that where the cutting edge is too far from the anvil part you can all ways add material/ weld on the anvil to take up the space at that point.TomC