I would run what the owners manual calls for and nothing else. Mine calls for 20W50 and that is what it gets, period. Just my opinion. As far as the brand, any well known oil company oil would be fine, such as Amsoil, Mobile1, Royal Purple, etc.
First I would not go with a 10w, too light in my opinion. 2nd, if it does not say it is for an air-cooled v-twin would not use it no matter what. Just my thoughts.:s