the part that's hard about the one piece thread on hubs is where the magnet will end up will change a lot assuming you don't use a key (can't really if you have a one piece thread on hub), the timing will eventually change on you after it runs for a while, what you can do is make a spacer hub like I just did and either cut the center out of the flywheel (some people use a hole saw then face it on the lathe), drill a hole for the magnet and mount the sensor with a hose clamp or something, the other option with this setup is to just make the piece that replaces the flywheel part, take a piece of round stock about the depth of the flywheel, probably about 1" diameter or thereabouts, cut a taper in the back with a boring bar, I've mainly used the trial and error method, ends up being around 9*, Ive probably not done it the standard way, but it seems to work, my boring bar is a piece of 1/8" HSS square stock I got from HF in the assortment thing they have for a couple bucks, I ground it so that it's 1/4 pie shaped, sharpened the end appropriately and go for it after spacing it up to center (my 7x12 uses 5/16" tools, so 1/8" is small and needs spaced up), a trimmed hack saw blade could probably be used to make the slot for the key, I've never tried it, all of the one piece hubs I've done have been for gas/glow, or the one I attempted to make a split ring to hold the magnet for... that didn't work out, will do it differently next time.

as for pictures, I'll head upstairs and grab my camera after a bit, I just finished the hub a few minutes ago and need some dinner

a couple notes, first you want right hand threads, with the engine spinning counterclockwise, the power stroke is pushing on the prop nut in the direction that tightens the nut, left hand threads are only needed if you want to switch the direction that the engine turns. the other thing I wanted to say is that I'm not sure it'll matter, but you might have trimmed too much off of the crankcase, it could need some of the support you cut off, when the piston is being pushed down, the crankcase is the only thing counteracting against it, since this engine doesn't have a bearing on the front and rear it's two bearings are both between the prop and piston, could eventually fatigue and break, but like I said, it could be fine, I don't know how thick that part of the case is anyway...