Thanks for the advice guys, I agree with the general consensus that it will need to be lightened considerably.

Wouldn't the power output of a .72 2 stroke be around the same as a .91 4 stroke?? It just that I already have 1 and would only need to buy 1 more, but if I went down the .91 4 stroke road I'll be looking to buy 2. I'm trying to keep the budget reasonable on this one.