In my experience, you are likely to find bisexual men in forums or places where couples are looking for a threesome. Most of the guys who are willing to share their wife with another guy do it because they feel attracted to other men, and once they have had this first encounter, they will hook up "one to one" very easily.
As a side note, funnily enough, bisexual men do not really care about your shape or form, they are excited about being with a man.