Bike looks nice. Are you contemplating a HT engine? Seems so referring to the carburetor.
1. With the curved down tube, most likely need a custom mount. Front/rear or both.
2. I don't know if the rear sprocket will fit, might need a hub adapter.
The more I look/measure it, I don't think its a viable option.
The crossing points on the tubes is where you will have a 75 degree "V"
To me it appears that the rear mount will need to be discarded, and a custom rear and/or front mount is needed. That way the engine can be mounted lower for head/spark plug clearance.