CAR RIM AND TIRE DESIGN DETAILS

SEE ATTACHED DESIGN I could really use some input here on this car rim mod. I took the first step in crossing over to the darkside by buying my first CT for my Yamaha XS650 hardtail Bobber. The tire I bought is a brand new never used MICHELIN XW4 215 70 R 15 complete with stock rim for the low price of $20. I know it’s kind of like putting the cart before the horse with not knowing how I'm even going to adapt this car rim to fit my bike but I have always been a believer that where there’s a will there's a way and I couldn't pass up the deal.
I know that it would probably be easier to install a CT on a MC rim but this is really the complete look I'm after and also I have never been one to take the easy way out. Now I'm at the mercy of you fine people here to help me get this thing mounted. I'm right now at a stand still with my bike build and I was hoping that someone had some first hand knowledge on modifying a car rim to fit a bike and if so could you look at the drawing that I designed and tell me what you think and whether it will work? The drum and centre hub of the mc wheel just happens to be the right depth for clearing the tire. I can't determine the best way to complete the unfinished side, (see drawing) filling the space and fitting the sprocket. Idealy I think that it would be good if I could run bolts right through everything starting from the sprocket to the center mc hub. I would like to keep the area in the centre of the car rim recessed as it is in order to keep the original look. I went with the drum instead of disc brakes only for appearance.
The bike is still stock and will be getting it's hardtail made up once I get the tire/rim set up so basically I'm starting with a clean slate. PLEASE HELP ANYWAY YOU CAN. Below you will find my proposed design along with pictures of the front and back of the new rim and pictures of a fellow XS650 builder with the car tire and rim only he went with disc brakes and his rim with welded steel plate comes right out almost flush with the tire, but mine won't.
I would appreciate any advice you can give or if you know someone who might be able to help. Thanks

The only idea I could suggest would be to cut the whole center section out of the wheel and weld in a steel disk,
drilled for your sprocket mount pattern and the axle. You could center it in the wheel rim for what ever offset you needed to clear the brake hub with a ring spacer on the sprocket side. The whole assembly sprocket - spacer - wheel - brake hub, could then be bolted together.

Not sure if all the pics are your buddy's build or not, but from the diagram, it looks as if you simply need a sort of a hub like a tube, with small pipes welded to it where the bolts go, like a center pipe with external or internal pipes attached all the same length to transfer torque from the sprocket to the wheel.
Then there is the idea you see on chops and dirt bikes at times, of a sprocket doubling as a disc brake if it's large enough.
Third, his wheel seems to stick out on the sprocket side far enough to just weld on the plate he has there, but in your drawing, it seems that your wheel doesn't go that far. Are you sure this is the true center and the drawing is to scale? I'm just sayin' that can make a difference.

About the only advice I can give is to take it to a machine shop and have them do it. Having to ask these questions, it seems as if your knowledge in this subject is about as lacking as mine, and anything either of us kludged up would be dangerous to rid on.