Clear, honest communication will be hard to come by in this relationship. Any evasions or half-truths that you engage in will confuse your friend to the point that they won't trust their perceptions of you -- and perhaps they won't trust you, either. Your attitude that the truth is a changing, negotiable thing will undermine the foundations of your connection and will make true friendship very difficult.
Even if there are elements of your past or your feelings that you'd rather not own up to, you'll be far better off in the long run being honest about them. It's up to you to give your friend a clear and accurate picture of the person you are, flaws included. Misunderstandings will occur frequently, and after a while, neither one of you will feel very heard or understood. A lot of the responsibility for clear communication will lie on your shoulders, as you're the one who will avoid it, purposely or otherwise. If this relationship means something to you, make the effort to be forthright and honest with your buddy.