Your best bet in my opinion is to check out this site for what you want. He has the motors you need, and all kinds of adapter plate for mounting such setups. If you cannot find what you want send Dan and email and he can make up custom gear for your needs. I have the dual 18v 970 motors for one of my setups, but have not run it just yet. Too many projects going at one time. Good luck in your quest for more power and more speed.
http://www.kershawdesigns.com/