Like Yuri I stress that you know for sure your water makeup. Are you trying for an identical style?
In my experience, limited as it is, I have found that this is almost impossible as my water changes season to season slightly, and keeping up with an excact profile is contrary to my lazy approach. Now I just keep the PH in line and add slight amounts to the boil to get my desired effect.
BTW you collect 9 gallons to boil down to 5 gallons? That is a lot of boiling.
How do you BBQ an elephant....first you get your elephant....