I assume you posted this because you were aware, or vaguely aware of some of the possible consequences of a Deca only cycle. Even though Deca Dick and progesterone induced gyno do not happen to everyone doing this cycle, it happens enough for you to be concerned. Remember, you wont have ANY defense against either, other than luck.
Personally, if I ONLY had Deca to work with, I just would find a better source (not too hard), or save up so I could do a proper cycle with Test, anti-e's and a progesterone blocker (Winny or RU486) so I could concentrate on gains without worrying about sides and wouldn't have to kick myself later because I was impatient, reckless, cheap or whatever.