The first Plymouth V8 made in 1955, was 301 C.I., I believe, was the first poly head only block, correct?
I'm thinking the Chrysler Windsor and Saratoga cars may have had poly heads on them before 1955 I seem to remember hearing about those cars having a 301 C.I. motor in them in 1954 to 1956, also but not the same as the little Plymouth poly motor, that you could use the Firepower Hemi heads on them if you needed or wanted a small C.I. Chrysler Hemi head motor
I don't know anyone who did that, I sure didn't