Just read this on a wiki... Says the 335 HP version got the 440 cam, heads and exhaust manifolds. However I was not around then I can only rely on the information out there.
383
1964 or 1965 Chrysler 383 B engine
The 383 cu in B engine — not to be confused with the RB version — was essentially a larger bore version of the 350 and 361, using a 4.25 in (108.0 mm) bore for a 383.03 cu in (6,277 cc) displacement. This venerable engine was introduced in 1959. Dodge's version, the
D500 had a cross-ram induction manifold and dual four-barrel
carburetors as options. In some Dodge applications, this engine was labeled as the
Magnum, while the Plymouth version was called the
Golden Commando. Both came with a dual point distributor in high-performance versions.
The 383 became the standard model Mopar performance engine for the next decade. The big bore allowed for larger, 2.08 in (53 mm), intake valves, and the relatively short stroke helped it to be a free-revving and free-breathing engine.
Producing a maximum of 330 hp (246 kW; 335 PS) (
gross) and 460 lb⋅ft (624 N⋅m) of torque for the 1960 model year, the 383 beat the 392 Hemi that had reached 435 lb⋅ft (590 N⋅m). The 1960 383 engines featured the same basic ram induction system as the Chrysler 300F's 413 RB engines (named
Sonoramic Commando when sold in Plymouth form).
The later 383 Magnum (starting in 1968) used the 440 Magnum heads, camshaft, and exhaust manifolds. This engine was advertised at 335 hp (250 kW; 340 PS).
