Sonomajoe

So I picked up a LQ9 short block rebuilt with ported 243 heads and LS6 cam with a carb intake.

I have a Demon 650 or 750 cfm carb. Would I be good using it if it's 650 cfm? Demon gives no info... It's the lamest customer service in history.

I know my buddy paid around 800 for it back in the day is all the info I can give.

Is there a way to test a carb for cfm rating? And if it's not the carb to go with what would be a good choice?