Careful -- the T-10s are fairly light duty transmissions. I have never had one that didn't slip out of second or third. Then again, I like acceleration. If he is selling it that cheap, it might already have that problem. You didn't used to be able to get gears and synchros for them but I understand someone is selling kits for them now.
A top loader is beefier, either the four-speed or T5 five speed. I have 155,000 miles on my T5 (I pulled it from an almost new '93 GT wreck in '93 and installed it behind a warmed up 302 in my '65 convert with a deep ratio, traction lock rear) with absolutely no problems. They cost more, but are well worth it in my experience. Gotta say, if it were me, I'd pass on it.....sorry......