That water profile is not too bad for lighter colored beers, but the alkalinity is likely to be a little too low for dark beers or beers with significant crystal malts and the mash pH may end a little lower than desirable.
Adding Burton salts would further depress the Residual Alkalinity and the resulting mash pH. Not a good idea. If anything, a darker beer made with this water may need some additional alkalinity to provide the additional buffering needed. My preference is pickling lime, but a little baking soda might also be used as long as the sodium content is kept below about 50 ppm.
I hate to say this, but the typically poor performing 5.2 Stabilizer product would actually help in this mash. This product tends to push the mash pH well above 5.2, but that could be a help in the case of a dark beer. But the problem with this product is that it adds a lot of sodium. Not really a good solution. The other alkalinity producers mentioned above, are better alternatives to 5.2 Stabilizer.
Chalk is another option for adding alkalinity, but its a little cranky in delivering its alkalinity. It should be dissolved into water along with a CO2 bubbler, but another option is to add twice as much chalk as indicated by its stoichiometry.
The other option is to just go ahead and use the stock water profile and brew with it. The beer may come out a little tarter than it might have, but you may like it that way.
Enjoy!