Carb conundrum

i've seen stock hi comp. 340 builds dyno around 280 making the factory rating realistic.I think the engines using the thermoquad carb peaked a bit higher.
I know of one 426 hemi built to stock specs that dynode 465 hp at nearly 6000 rpm without water pump,alternator,fuel pump or fan and had open headers.With accessories this would be very close it the factory rating of 425
i'm not convinced that a 400 hp 340's are common or as easy as some claim...