I don't know the Champion brand, but did a lot of research on generators about a year ago.
6500 watt, with 2 breakers that are rated at a minimum of 25A each is what seemed to be the minimum standard, so that is what we bought. We have never had any trouble with it running a double blower, fans, lights, etc..
No matter how you slice it, it will cost a minimum of about $750...unless you got a heck of a source!