850 cfm proform carb on 318!!!!

Moper........
Normally I double the cube to get the cfm requirement.
(conventional thinking)

This is on a single plain intake that pulls the complete carb cfm.
For example: I use a 750 holley hp on my 360 with a M1 single plain intake.
360 x 2 = 720 cfm.

I can also try the 850 on my 360 at some point i guess.
My 400 big block ,when ready, will get the new 850.
The 400 is using the new victor 383 intake (single plain)

Just trying to improve my choices while keeping the cost down.