You are completely forgetting the other claimants in CLASS 19, with that said the old WAMPQ's only own approximately 43% of that 75% total.
Yes there are only 3 Million P's but your forgetting the 20 Million K's plus the largest claimant which has a 53% claim (TPS/TPG) forgetting that other entity's initials.
So drop your expected payback by approximately 50% and you will be closer to reality.