Nobody here has any confidence in the D-Series. Ever think of it this way?
For the cost of your swap (say around $2500-3k when its all said and done) you could have easily built that D-Series (Pistons, Rods, Sleeves). Now, say that B-Series wasn't enough, and you decided to turbo it stock.. another 1500-2k on a decent turbo setup +tune puts you at almost 5k into the B-Series and you're still stock turbo'd.
Take that money you just put into the turbo for the B, and turbo the D, and you already have a built engine that's ready for it.
IMO, stick with the D-Series. Just as capable of making power with the right parts.