Craig, You have a lot of options for the tranny cooler. It is relatively simple to installl. Your transmission should have two lines coming out of it going to the radiator. One is the out line and one is the in line returning from the radiator. You would simply plumb the cooler into one of those two lines. The external cooler will come with hoses and attach with clamps. B&M makes several universal models that would work well. They may even have one specific to the Z on their web site. Any universal B&M cooler from Pep Boys would be fine though, and the cooler itself is attached to the front radiator supports with screws or a nut and bolt- you'd have to look at the package.
David, you have a good idea. The power steering cooler would work, except the hose ID would probably be different. I haven't looked at the Z's power steering, but typically it is larger than the small AT lines. Power steering fluid and ATF are almost identical, and can be interchanged if need be for emergency use, so other than the hose size, the cooler would be perfectly suitable for AT use. Not vise versa, however, as power steering coolers are typically rated for the higher pressure than that of a AT. Hence why they are more expensive than AT coolers.
Will

 

David, Will
Thanks for the suggestions. I'll look at both possibilities. I guess the important issue is getting one that fits physically in the space available.

First thing though is to get tires for the car. My rears are now slicks but the damn fronts are still hanging in. They aren't to the wear bars yet. Although quite abused since Saturday they still are in pretty good shape. I'm considering Kumho SPT's or the BFG KDW's. The Kumho's are cheaper and both have similar specs. With evrything else I've got going on right now, maybe I'll just go for price.