Just a quick question here...
What model is your Del Sol? If you have an Si, then you already have a D16Z6, which has VTEC. If you have a base model, then you've got a non-VTEC D15. You could easily convert the D15 to VTEC with the head rainer is offering you.
Keep in mind though that the transmission is part of the equation. If you're looking to have a fast D15/D16, then aside from just the motor I'd also look for an EX or Si tranny. The gears are shorter and will help you accelerate faster. The transmission that's attached to your D15 has long gears; good for gas mileage but not good for going fast.
One more thing to think about. If the B16 is what you really want, then do you really want to spend any money on a temporary motor swap? I mean you could take the $500-$700 you're going to spend on a VTEC D-Series and save that towards a B16 instead. Unless there's something wrong with the motor you have and you need to swap it now I just don't see the point of spending a good chunk of money on a motor that's not your first choice.
Are you going to be doing the swap yourself? Or are you going to have a shop do it? Consider that too. If you're having a shop do it then why pay for two swaps?
If you'll be happy with a VTEC D-Series than go for it, but if what you really want is the B16 then I'd say skip the D and save your money.