OS 108 would be fine in a Kaos90. Plans are at
http://www.airagestore.com/. My Saito 120 will pull it straight up outa sight. Foam wing at
http://www.eurekaaircraft.com/foamwings/wing-k.htm. The cost of shipping the wing will be $$$!
Keep posting.
Skyhawk
Sandusky, OH