Congratulations, you have done your research and you are almost there to passing this crap. You're right, head hair grows about .53 inches per month and body hair, depending where, is almost this rate. But I'm guessing that if your hair at 71 days clean is a little longer than an inch you have a little bit of dirty hair on your head on the very ends, not much though. That's because there is "lag time" because your body will still deposit metabolites for 2-3 days after you stop smoking plus it has to grow out far enough from under the skin. So this usually adds up to about 10 days after you stop but I like to be a little more conservative and say 15. So actually you did well by waiting 15 days to cut your body hair. So is this little bit of hair going to be enough to cause you to fail? I don't know because you said you are a heavy smoker. I wouldn't cut my hair less than about 3/4 inch but that would probably get the last little bit. If you don't want to cut it again you have have already hit your head with a lot of treatment and you still have the Zydot so it seems that you stand an excellent chance of passing based on the clean time and what you have done to clean that last little bit.

Good luck!