Astro vans use HB also. I am not sure what year they started though. For the BadAst build I picked up a pump from an early eighties 1 ton Chevy truck and repurposed an HB unit from a '95 Astro.
Pay attention to the HB units as some of them come straight out from the firewall (the '95 Astro) and some of them have about a 15 or 20 degree down-angle from the firewall. I parted out a '98 Astro that had the down-angle booster.
get all of the lines as well when you are picking. You will probably want to replace them anyway but they will give you the correct length and any good auto parts store can build you new lines if you want to go that way. The fittings are only a few dollars each and the store should be able to crimp them for you.
Mark