Most bill acceptors will fit in to a pinball door (if you have a pinball door with a BA mount). I have even had pinballs with upstackers in them. The pinball door should have two mounting holes on it-- one for an upstacker, and one for a non-upstacker model. Some upstackers WILL be too large, so i'd go for a Mars unit if that's what you're looking at.
Vending BAs are out-- they won't fit.
The older Mars unit you are looking at probably won't take new 5$ bills, but it should fit.
Check to see if your pinball machine has BA spacers either in a baggie or screwed in where the BA goes. If you don't have a spacer kit, you're going to need one in order to get the BA to fit right.
If your BA deal falls through, I'll sell you a DBA-01 dirt cheap.
Good luck!
APf