No it wasn't... The 440 6 pack cam was also the same as the high performance 440 4 bbl cam.... Which is the same cam as the high performance 383 4 bbl cam...
Here's the camshaft specifications from the 70 Plymouth service manual:
Unless you're talking about putting a big block cam in a small block, which wouldn't fit....
The 6 pack engines got the same camshaft as the counter part 4 bbl cams for that same engine size... Whether it be a small block which took the same cam as the 340 4 bbl or the big block which took the same cam as the 383 and 440 4 bbl HP cam....