Hi Dave,
Great that you scheduled a visit!
I don't know anything about the bike, but in general I think you should ask the seller if you can ride it for several miles on decent roads. Maybe he'll ride with you and show you a nice loop. Maybe he'll ask for a deposit in case you scratch a lever or something, but you need more than a ride around the block. Take your shoes, bike shorts, gloves, pedals if necessary. Have your gf do the same. Take some tools also to adjust the seats or install your pedals without having to borrow his. Take water bottles also if you'll need them. Check tire pressure before your ride. He may be too busy to agree to all this, but then again, maybe not.