[rjSupra]

Ok, tossed new battery in her, and she more or less started right up.
Nice mellow idle. It's 25 degrees F here now.
I drove her about 30 miles through small country roads and then stop and go lights city driving for 20 minutes.
Then I dared to prod her up to about 50 and 60mph. No leaks after pulling over and checking the whole way.
I hammered the throttle pretty good and got on the boost about 4 times and was up to 60 and 65mph on side highway.
It all seems pretty good right now.
After a cool down in my new garage, no drips at all, and I undid the rad pressure cap and the fluid level looked the same. Levels looked ok in the overflow reservoir - although I need to tweak the level anyway, and my birdcage light is on (so is the e brake light but the car rolls in neutral).
So... after months down I might be able to drive it again! Of course I've got this nasty power steering leak to tackle next...
I guess the 90 hose was probably evil all along on this one (although could have been the water outlet housing gasket - I guess I don't know).

Thanks all for the help and input, thanks Toyota Supra forum, never could have done this without all your help!!!