If you're not in a huge rush just yet, I highly recommend that you get and read Pukka's Promise. It will cover a lot of what you're looking for in a lab, and it's a GREAT read as well.
I'd also recommend that you find a labrador retriever focused forum, and go there and ask for breeder referrals and tell them you're looking for field line pups. Most of them can recommend who to consider and who to steer away from (if it's anything like the golden retriever forum I'm on).
With GR's, you look for clearances on hips, elbows, heart and eyes. Not sure with labs if OFA clearances are as important on elbows as hips, since I didn't research labs when we got our Noah.