I have to agree with crazydood, and disagree at the same time...
You 'should' only put 2.2 tires and rims on your RC10GT. That doesn't mean you can't do it. It just means that it isn't going to be an easy bolt-on.
Also, there is a big block conversion for the RC10GT. I can't remember what company offered it...I've seen it advertised in the magazines.
Go ahead...Build a mutant monster...Post pics of it when your done.