Varied indeed, and if you want 'from the factory 2.02 heads' flow numbers...then you need to ask someone who actually is old enough or in this game long enough to obtain a set of next to never run 915 2.02 j heads. Mine flow 225-228 depending on port, from the factory with tulip valves.
The 1.88 version j flowed 210-215cfm.
Without push rod pinch tubing they will go to 290's if the porter knows what he's doing.
Experience is everything.
As for what they flow mildly ported? -high 230's to low/mid 240's