...BTW your Bieber avatar is awesome.-Malone
to me i would go the easier/cheaper route and use an he211w. thats a tough little turbo and should be easy to adapt to your current manifold.
he can get one drop shipped from holset factory for about 600ish I asked about getting one a few months ago.
Sorry Gizmoman, I thought you knew of the availability. That is why I suggested it. He should still have a post in the for sale section on the new ones IIRC.
i think its hard to say with out someone using the turbo with a simialr setup to yours. but from what alcaid had said it spooled very quickly on a 1.6 engine with 1.9 head, no port work on the head either, and made 173whp on that car as well, so with your van having more displacement it should have no problem spooling the turbo, and peak power would depend on how much boost you want to run.
I'd get Libbydiesel's input - he's the best source of VNT vs. Wastegate +/-around...I've got a VNT-15 from IDparts on a mostly stock 1.6TD. - - - it was $840 IIRC (ALH standard turbo w/ integrated exhaust manifold). Also a mech vane mechanism homebrewed.