As Ive already said, I am sure a PX crank does NOT fit. again youll have to confirm this with A.N.OTHER but Im sure that is correct. DOC? Also, youll need a voltage regulator. Use the centre boss of the rally flywheel to the px flywheel.
From memory, which is a tad foggy due to excesses of beer, when I did mine (18ish years ago) I had to use the centre boss from the femsa flywheel mated to a cdi type flywheel, I used a pk one I think, and filed a lot of the stator plate away to fit to the rally engine. It was a long time ago so Im willing to be corrected. I know it worked and then I did same for a lambretta. The centre boss was secured by 6mm csk allen bolts tapped through the flywheel and then half-nut nylocs locked them, with mucho loctite. Never came loose. The px taper doesnt fit a femsa crank, and a px crank doesnt fit the femsa cases/ bearing housing. ( correct me if Im wrong someone, it was a long time ago. Something has stuck with me cos I reject the idea of a femsa type engine as a base for a tuned 200 now!) Give someone like Kegra a call.
Try the BBS board. I’m sure they do it over in the States all the time. I think they use a PX crank ,stator and flywheel with a T5 bearing but am not 100% on that.
Try looking for part 5001900 on this site. cost was €359 a couple of months ago.