Sounds like you've got a cool project going on. Don't think I've ever seen Rec. Trike done with such and engine, but it should be good with such a low center of gravity and all.
If you have time maybe you tell us about:
1. What type of brakes you plan on using?
2. What rear tire size do you have in mind?
3. Do you plan on using any lighting? Having turn signals along with head and tail lights would be pretty sharp imo (as would rear view mirrors).
4. Will your trike be licensed for the road?
5. And finally, what are your estimates for the weights of this vehicle (including Gross)?
Sorry for all the questions...
Btw, welcome to the Motorbicycing forums!