I had to do a little hunting to find out what a "90" was since the only two lathes I know of on the market at the moment are the 24-45 and 24-42 (guessing on the latter). If your find is in good shape it's probably a nice piece of machinery since it's a vintage piece of Powermatic. Here's a link to a page where the guy did a neat resto on one.
http://vintagemachinery.org/photoindex/ ... px?id=6994
His doesn't sound like it was in all that great a shape from the description of the work he had to do on it. I'd give it a thumbs up just fer braggin' rights if it's all together and runs like it's supposed to.
Be sure to check the headstock bearings for wear. Are the ways in good shape - not knicked up or rusty? Any tooling come with it? Like live center, spur drive and so forth? Is it a common taper in the head & tailstock? (Morse 2 is most common as I'm sure you know)
Wow ...
Post a photo when you've got it set up!