Damn these problems -- they're tough. But I like them.
Initially, I'd think bet remaining # of blacks minus # reds divided by # of remaining spins of your session bankroll (i.e.: your advantage). First bet (67-33)/100 = 44/100 = 3,400 units. Now you'll either have 13,400 units with 66 black and 33 red, or you have 6,600 units with 67 black and 32 red.
I can't imagine that being the proper solution, though.
Or perhaps you wager 1/(red+1) of your BR. That way if you hit all red in a row, you'll end up with X units, all black and no reds remaining, and you would be betting 100% of your remaining BR the rest of the way.
As far as what happens once you know no red are remaining -- you parlay the rest of the spins.
What about the event of when red = black or red > black? I can't imagine quitting at that point would be proper, but not sure at which poin you'd quit because knowing how many of each more (that knowledge) is overcome by such a large disadvantage.
Edit: Nevermind, since youd just bet red and get an advantage that way. I'm stupid.
Edit2: There also may be a way to maybe get a larger advantage by betting the columns or other outside bets, not just the even money R/B. But don't quote me on this, more of a possible solution.