yes, I've done a fair bit of research and asking, and came up with these numbers.
Bear in mind these numbers are approximations
When diluted at about 1.050
Ca: 50-100 ... Mg: 0? (no info) ... Sodium: 115, (or well over 100ppm) ... Cl: ~30 ... SO4: ~60
Use this as your source water profile in the water chem section, and also keep in mind this profile is good for when you're using approximately 2 cans of LME or 2 x 3 lbs bags of DME. Adjust accordingly as you increase or decrease amount of extract depending on the beer.
Biggest issue I've heard about Briess extract is that they use municipal water in Chilton County Wisconsin, and their water is very high in Sodium. I've since switched to Muntons extract in my shop, and Muntons QA department was kind enough to contact me back and let me know a more exact profile.
Muntons diluted at 1.050
Ca: 21 ... Mg: 0 ... Na: 4 ... Cl: 10 ... SO4: 14 ... HCO3: 42
A much softer profile that allows for much higher success in softer beer styles, or better mineral manipulation for your IPAs and such.
Hope this helps!