Werby might have some insight on this?
pl
Gonkulator puts the 352/360hp at about 350hp gross iron manifolds.
I think Ford just wanted to one-up Chevy's 348/350hp rating.
Gonkulator puts the 352/360hp at about 365-380hp in NHRA stock legal trim which is NOT assembly line trim at all.
Some engines made 20-25% more than their ratings with NHRA stock legal prep.
You can pick them out because later they'd get factored, and still win their classes.
Part of where the 352/360 and 390HP really excelled was the awesome midrange of those ahead-of-their-time C0AE-D heads.
Gonkulator puts peak torque about 395 ftlb in production trim.
The 390HP, because of these heads, Gonkulates overall as strong as the factory 406.
I think Ford thought it would have been rude to larger engines like the 409, 413, and 421 to put these chambers on the 406.
So they took a step backwards to a soggy dead chamber, and added a soggy deck to boot.
In other words I have no idea why Ford gave up on those beautiful chambers.
Agree w Royce on the big MEL's - (partly since he is the source for much of my MEL dyno data!)
Ford really liked to overrate their vanilla cruiser engines:
352/300 Gonkulates to about 270 real gross HP
390/300 about 280 real gross HP
390.315 about 290 real gross HP
428/345 about 310 real gross HP
429/360 about 320 real gross HP
430/360 about 320 real tross HP
As I understand it, the really early 430's made more power, still not their ratings but closer, but got detuned for smoothned, avoiding knock, etc.
BTW, I am convinced that big early Hot Rod dyno test on the 361/303 was reporting more like NET horsepower for most of the tests.
The vanilla FE is overrated but not by THAT much.
Still I'd welcome some precidion-prepped throwback dyno tests of the old stockers.