I can't comment on the Unisaw, I would think if you have the welding skills you can make any kind of motor mount base you need, go through Grainger's they might have something you need.
I do want to comment on forming a partnership, if you don't mind. As a former salesman at the wholesale level for 20+ years, and later business manager of several contractor related businesses, I called on hundreds of HVAC, Plumbing, Gen Contractors, and other construction related businesses. I have seen many successful partnerships, and unfortunately I have seen more failures. Like all things it isn't how you start it is how you finish, many partnerships start out great, but often end not so well. Next to a marriage a partnership is the most collaborative-dependent and interdependent and often intense relationship you can have.
You both should read a couple of books on forming business partnership, which could give you both the questions and answers and agreement necessary to successfully move forward. Besides the trust, workload, compensation, and communication issues, liability and protecting yourself ( home, assets) is another important consideration.
Good luck, having a good friend that could be a great partner would be a wonderful thing.