speed bag could be an option for you. both that and the punching bag in conjunction with a realistic diet. I see you achieving your goal. swimming is prbably the best idea though, considering the rehab qualities with treading water. one other thing, don't forget you burn a lot of energy while weight lifting. If you just use the machines there i'm sure you could burn off some cals on the pec deck, lat pull down or something.
do lots of situps. I think they are referred to as crunches. lay down, knees bent, and keep your hands on your thighs. lift yourself up till your hands get to the other side of your knees. do this until you burn out. use that number and do it 3 more times. 4 sets always gogo.