Thanks. I ended up drawling it with the 2.5/30 mm dimensions mentioned by floobydust, with that hint I found a few more datasheets for an (I hope) analogous part, they all agreed with the 30 mm.
It would seem that GBJ is the form factor. I had less luck finding a heat sink from a reputable source, although sleezBay does have something that looks like it'll work.