Legalities aside, I don't know why you'd want to buy a motor that at best is 16 yrs old just to save a couple hundred bucks. There are supposedly some inferiorities in the head design also with the older ones. Plus those old swaps you need to change the injectors, they come with cable trannies, blah blah.
IMO, it's the tranny that costs the most on the later swaps, and you'd have to get a hydro B16 tranny anyways so in the end you don't even save that much getting the old one. OBD1 is alright, easy to convert.