There are plenty of threads here about tires, just do a little searching.
If price really isn't a big deal go with one of the more well known brands (Avon, Dunlop, Pirelli, etc..) as opposed to some of the Chinese ones. (Also I would suggest that you replace both front & rear tires at the same time)
If you do only replace the rear, make sure that you get a tire that is made for the rear. 'Vintage' tire sizes are somewhat limited in selection.
-JP