That seems like too much trouble you would have to convert to rear wheel drive. and where would you bolt the rear end and if so what would keep it from just ripping out? It would also take alot of custom made parts that just simply don't exsist. Sell the mx3 and buy something with a better platform or build the hell out of the motor you have. these two options are going to be thousands of $ cheaper and will be less aggivation and quicker to put together.
Although an mx-3 with a honda motor does sound intersting
And an mx-3 with a rotary and some turbos is just plain balls