Check out the Hamtramck Historical site. Go to Library, then Color & Trim Selector, then 1965, then Dodge icon, obviously choose Coronet.
P4R and H1R (500 & 440 interior codes, respectively) refer to trim level, not color, which is the R. P = Premium, H = High. The 4 and 1 most likely refer to buckets vs bench.
Similar to how interiors were coded on the later cars.