THey should not deny you for that reason. THere are many ways to keep your health in check and take extra precautions just like anyone else when handling blood. Know that most health care professionals recommend anyone with hep B check their health status every 3- 6 months depending on the severity. It not only tells you about how contagious you are but also if future employer asks or patients ask, you can provide a satisfactory feedback.
Your friend may have received antibody as a child from the mother, he/she will most likely have negative antibody no matter how many times you receive the immunization. He/she may also need to have surface antigen test. Negative means you had or have hep B. There's also a third step called Hep Be antigen. It may be negative, indicating you are not contagious. This last step tells you how many active virus are in your body.
good luck!