Dcoy70,
The 91 will be a great engine in the UCD46. I've read where others (raideron and gjeffers) are even flying this beauty with a Saito 100. They speak like it's awesome. You will be impressed with that engine. I would start with a APC 15x4W prop. This will keep the speed slow and the thrust high. This equals FUN. THis little jewel will fly wonderfully slow and will light up the sky when you want to start that 3D thing. Or....so I've heard. Neat airplanes. I can't imagine any true RCer without one of this babies. And Tower is offering them for $125 delivered right now.
Thanks
Bud