Water cooling was on all 85+ turbos from the factory. It could have been replaced, who knows.
The engines are the same from 84 through 3/87. 4/87 through 89 had the W series engines. Here's the differences: http://www.engr.colostate.edu/~radare/wserieschanges.html
Personally, I'd just turbo your NA block and keep the 9:1 compression. That's what I did and so have several others without any problems.