Decided to name the latest brew "Hop Monster":-
The brew has been split into 20 bottles and 7.5 litres in the keg.
The plan is to make a brew light on hops tomorrow... that will be added to the keg. If the simple maths works then that should get:
56.1 IBU = ( (7.5L * 78.2 IBU) + (9L * 37.8 IBU) ) / 16.5 IBU