Like hawlee^ said, I had one of my tattoos on my chest area- which people often compare on the pain scale with the rib area.
It was painful after sitting there for 3 hours, but all in all it was bearable. I'd say probably on the 7 area. Of course, everyone has a different pain tolerance. I consider myself a person with high pain tolerance, so a 7 is actually kind of high for me.
Most places will tell you not to take anything before a tattoo session, but I took 2 ibuprofen's before my chest tat session, and I know it helped hundreds. So, if you're really worried about it, don't be afraid to take a few before you go in (just make sure it isn't Aspirin, or anything similar, because it thins the blood and will make you bleed more!)
Hawlee was also right, because when they got to my pec/boobage area, it hurt the worst. That was the worst pain.
Best luck to you!