I thought I'd chime in and discuss the basics on choosing a forklift motor. In general, I advise people to look for a motor that weighs between 100 to 150 lbs. The heavier the car, the heavier the motor needs to be to push it around. The way I see it is, you don't want Peewee hermin trying to pull you around but you probably don't want to feed Hulk Hogan either, lol.
When searching for cores, look for insulation that is wine colored with yellow banding, brush leads that are still copper color and not scortched, and a commutator that isn't grooved or pitted. Don't be afraid to remove the cover band and have a look inside the motor (and while you're there take a pic to send me). I get a lot of "I wish I had wrote you before I bought this emails" and it's a bummer to read them honestly. I'd bet that almost half the motors I've built are still not up and running yet, so you might not need that motor as fast as you think you might. Sometimes looking to eager to buy not only drives the price up but might also cause you to buy something ill suited for your needs to boot.
Look for armatures that have a commutator with a large bar count as the larger the bar count the higher the voltage it'll take. Also, look for solid field leads (if you're looking for a series motor) or you might end up with a sep-ex or compound wound motor that may not suit your needs. Shafts can be one of the biggest issues in using a lift motor so make sure the shaft is something you think you can attach to or modify. There are motors I reshaft, but there are others that aren't as easy to do, or have no "standard" useable replacement shaft avaiable and then you're looking at needing a custon shaft made which makes them cost prohibitive.
Choosing the right motor isn't rocket science (unless you're a racer, hehe) but does need a little thought thrown at it so the end results are rewarding and meet your needs.