I agree with EC121 on the "power beyond its specs" Bill. I've never owned one of the TT GP series, but I've always heard that the GP-42 is a real stump puller. That'll power your Kadet just fine and you will get many years of service out of it. I think this may be a better manual link Carrellh:
http://mms.tiger.tw/upload/2007-1-30/20071308357.pdf Your link only goes to the .28 but it's probably all the same info. The guys at the field can help you Bill when you reach that point.
Oh and as for your original post Bill..... I love the OS FP & LA lines. They're easy for someone like me (not an engine guru) to tune and they run forever with a lot of abuse. Disclaimer: Not recommending abuse.
If you're buying one, go with the .46 because the .40's are discontinued like was mentioned. I've flown a 6 1/2 pound plastic SPAD trainer with a .40LA and aside from a pretty long takeoff run, it flew just fine once in the air. Don't know how much vertical you're going to get out of it, but it flies fine.
I agree that you're going to get more power out of a ball bearing engine but I've bought a ton of OS FP & LA bushed engines off the internet really cheap and build my planes to somewhat fit the engines because a lot of people say "you're going to get a lot more power out of a ball bearing engine" and sell their perfectly good bushed engines cheap.
Have fun!<br type="_moz" />