John,
If you decide to try dairy whey out for better coloration, I used 4% of the total flour weight. I also made a dough ball this week with 10% dairy whey, but didn't get to try that dough ball out. I froze it and am going to try it out next week. The reason I am trying 10% was because that was at the advise of Tom Lehmann. Just watch your bottom crust if you even try 4% of dairy whey, because the whole pie did brown faster for me.
Norma