If this plane rolls to the right with increasing airspeed and one wing is heavy, its the left wing. Look at it like this, at zero airspeed there is a left rolling moment caused by the heavy left wing. At a given airspeed you trim for level flight and the ailerons are producing a right roll moment. Now increase the airspeed and the out of balance moment stays the same but the aileron induced moment increases causing a right roll.

Get some automotive stick on wheel balance weights and put a couple of ounces on the right tip, fly and retrim and tell us what happens.

Malcolm