The 950 is just a number. It's got 750 sized venturis keeping the booster signal up/high.
Dual plane has nothing to do with the suggestion. Every engine I can remember picked up hp/tq running a 950hp over any 4150/4160 style 750.
Good that it's leaving matted. No accelerator pump/transition issues to deal with.
If that calculator was so accurate, why is it that the 360 I had ran better at the track going from a 750-950hp-1050 dominator when the perfect carb was a 660cfm IIRC... hmmmmm.. GARBAGE!