How many CURRENT owners of real '74 360 Duster 4 speed cars on here?
I realize the early 340 made more power than each subsequent version.
The performance holy grail often being the 1968 4-speed cars thanks to their slighter hotter camshaft.
The 360 really never made more power than the 340.
The most fair comparison is the 1973 340 vs 1974 360.
Not sure what "calculation(s)" you are performing, but I have to disagree with them.
All things being "equal" and factory stock, there is no way a 1974 360 car will make more power then an early (1968-70) 340.
P.S. The net horsepower ratings started with the 1972 model year vehicles.