Fuel volume starting point 16-71

Evening,
I am trying to help out friend with 16-71 Hi helix sitting on a BAE 5 heads 526ci with 4.5 crank.
Thinking of turning blower around 30% or 40%, in a lightweight altered style chassis with clutch and 3 speed.

Whats a conservative starting point for total fuel volume at 8000RPM in GPM.
He is using a Waterman .900 pump and is thinking of flowing to make sure is still good, I understand these should be around the 19.7 mark with internal plate mod.

Appreciate any help
P