Factory 68-71 340 puts 325HP on GM Dyno

Thiink about it:
You go up from 318 to 340 cubes less shouding etc.
Up the size of the valves and ports
go to larger intake and exh manifolds
install dual ex
larger cam
8.8 to 10.5 compression
dual point distributor and other misc teeaks and then:

you claim only 45 more HP than a 318 2b ? Comon mine back in the day was factored at the track at 325 was the rating the NHRA gave a 340 for a stock car.

Chevy had many 320, 350 and a 370 hp 350, Also I can show you documents on the WAY under rated Z/28 302 in 69 and the cross ram versions that got only 290 hp ratings. All put out close to 400 hp and have been tested many times over the years to prove it.

I think it was several factors
1 insurance cost etc
2 try to fool the competition.

They did the same thing with a 426 hemi, tell you what it made at a certain RPM, but not the peak HP.

And by the way, I have an all origional documented 70 Cuda with a 340, it is a mean little go getter. Even with mild 3.23 posi will smoke the 255 60s 5-6 car lengths with no power braking and many I saw at the track back inthe day would pull a high 13 or low 14 stock with out slicks.