The 1600 doghouse cooling shroud and fan are quite sufficient to cool a 2 litre type4 engine.
The type 4 has a bigger oil cooler so makes better use of the air flowing through there (it requires modification to the dgohouse cooler tinware to fit the larger cooler).
And the type4 engine has about 30% more fin area for the heads (compared to the type1/3 engine), so it makes better use of the cooling air there too.
Joe Cali
http://home.att.net/~nextgen/index.html wrote a very good manual on the conversion of Type4 engines to upright cooling.
And yes - Sharpbuilt in QLD make kits for either the doghouse cooling shroud or the Porsche shroud if you don't want to do it yourself (they get a mention in Joe's manual).
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.vw-resource.com