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Nope, do you? Any basis for your guess? 
seriously, I thought you were joking on your first post, but in case you were not....
If you are referring to this emblem (picture below). A 1966 emblem only used on Hemi Plymouths (no Dodges) to identify that they had a 426 Hemi under the hood, and only used for the first half of the year because few people "got it".
Then used/connected to later year (Dodge & Plymouths) to identify big block engines for some type of special High Performance usage? No, I don't see that as being very likely at all..
My opinion: Any 440 Blocks stamped HP meant nothing more than "High Performance Application", and "2" for Second Shift. That's all I make of it.
HPP was referenced back in the late 50's. Personally I could care less if it is stamped HP or HP2, does not mean a thing unless you match it up to a known six pack VIN. We have all seen C bodys with both stamps.
Amazing how an unchallenged lie can become the absolute truth.
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