I just add good old ascorbic acid to my sparge water, and don't worry about sg a whole lot. Never have a problem with tannins or phenols either, most likely due to the pH being too low. Fwiw your recipe in my system would yield an OG of ~ 1.068 and would probably be on the high end for an 80S, maybe a 90S? At any rate, sounds like you have a real winner, hope you have many more happy brew days to come!
Prost!
Michel
