422 dyno fail

Not the carb at all. A stock 440 Magnum made 375 hp with a veeeery mild cam, & a dual plane intake & a 750 cfm carb of similar design.
Carb is more than big enough with a single plane intake.
Did the dyno operator check the carb to see:
- if it was getting WOT
- if the secs were opening
- if that carb has a choke linkage, it can stop the secs from opening if misadjusted