Here's more detail about how I treated the water for the 1845 clone, and the thought that went into it:
Here's about what my water is like coming from the Orinda treatment plant in the SF East Bay:
Ca: 10.0
Mg: 1.0
Na: 8.8
SO4: 17.0
Cl: 13.0
HCO3: 34.0
I'm a firm believer in following the SO4:Cl ratio guidance that John Palmer has talked about, and I also know enough to realize that I don't know everything about water, so I adjust only a little bit, and in small amounts. Seems to work well for my water and the way that I brew. The SO4:Cl ratio is close to balanced in my water with no treatment at all. Burtonized water is highly balanced towards SO4. So I added enough Gypsum to firmly put the balance towards SO4, by about a 3:1 ratio. This also had the added benefit of putting the Ca up near 50ppm.
Just a little water treatment, not a lot, just enough to accentuate the hops, and certainly not near as much as if I was attempting to "Burtonize" the water completely. That hasn't worked for me in the past, I've found that it throws everything else off in the water and it tastes coarse, "salty" and treated.
I hope that helps. Give the 1845 a shot, it's an awesome beer!!