It all depends on who you drop man. You aren't really getting a two for one deal, ever. Because you always have to drop a guy. So say you drop Barbosa. See if the guy's interested in Barbosa. If he is (or maybe Q or Nelson), then try to include them in the trade, and get more for it. Maybe get an upgrade on Harrington or something, depending on the guy's lineup. If you're going to lose the guy anyways, then why not include him in the trade, and try to get a better player in return. That's my advice anyways. It'd help to see his lineup.
But yeah, if you want my opinion on the actual trade, then it would be a good trade. Kirk isn't that much worse than Chauncey, and Al would definately be an upgrade over whoever you drop. So pull the trigger if you want, but if you're smart, make a counter offer where you include the guy you want to drop anyways.