actually they have about 90! haha. Personally I would go LS but that's just me, you can find them a lot cheaper and more common. but you will have to convert it over to mpfi before you do any swap.
It is possible to see numbers out of the D15b2, you could probably get it to about 200-220 hp for 1500, mini me swap, port and polish, turbo, basic bolt ons, and an amazing tune. of course you could do more but thats just basics.
The B16 depending on what model you get it has about 150 hp, for that you may have to convert it over to obd1 (correct me if I'm wrong) model depending. for that you would have to get the different motor mounts, axles, ecu, harness, and trans...if you're not already getting that with the swap. But this would probably be the more reliable choice seeing that it's got 50% more power and it's still stock.
Or for even cheaper you could but a DOHC ZC engine and it's a direct swap and they are pretty good engines for d-series.
It may sound stupid but when it comes to engines you can't go wrong when it comes to building..if you think a head at least. if you build it and it breaks, rebuild it, if you can't rebuild it, swap it to something better.