OK first thing first. You are on the right track and bigger wheels are helpfull many times. But do avoid the temptation to change an airplanes CG to make it taxi better this is always the worst thing you can do and I hear fellows who have been around awhile suggesting this to new folks.

Alway the CG is set to acheve good flight characteristics not necessarily ground handling. Now one suggestion is to simply set if you have a capable radio (almost all but the cheapest do have dual rates at least on elevator and ailerons) the high elevator for more throw to use only while you taxi.

Now back to the bigger wheels and yes Conventional gear is used in the full scale world to indicate a taildragger. What exactly do you have for main gear, is it sheet aluminium or is it piano wire. It is no problem at all to find larger wheels but we need to know the kind of axle and it likely size. In most forty sixty sized stuff it will be 5/32. If the larger sized wheel only have an 1/8 axle size then it is normal to drill it to what is neccessary.

So what kind of main gear do you have?

John