Yep you are right, I ended up installing the front wings and bumper and badge plate from the S2 , basically the whole front end! I had to drill out all the spot welds on the S2 member that the airfilter tube goes through and I had to lower my Radiator a few inches. It was a bugger of a job but worth it!
I get on well with the "Porscheshop" parts suppliers in the UK and they have a couple of clients who have dropped 968 engines into old 944´s. 240HP!!!
The shop you mention is very expensive to say the least and new parts can be found alot cheaper..
If you had the full s2 to butcher why didnt you use the rad and bottom bracket? every thing would have just fitted in nice, and you could have saved yourself alot of work.
With the 968 motor in i think they nick named it the S4. Again there would have been alot of wiring headaches as the connector from engine loom to the the loom from the dme was different.(but well worth it in the end)