Dont bother wasting money on the D-series motors. Just save up and get a B-series and work with it.

B16a vs LS: I had a ls motor in my Crx and I ran a 15.2 @ 91mph with an exhaust and a hot air intake. Its torquey so its really good for a daily driver. However a Crx w/a B16a will hand me my ass easily-1/4 mile. The car is torquey but it lacks top end...it struggles above 6k rpm. If youre thinking about going NA Id get the B16a swap and when youre ready just swap in the LS block. Since I had the ls swap I had to buy a b16a swap for the headtranny and ecu.

If youre going turbo (its kinda difficult to get the pipings in there with a B-series swap) then its a toss up between the two. Most people would use a ls tranny to stay in boost longer and the ls has a lower compression so you can run a little more boost. Hope this somewhat helps.