I agree with Redhorse.
The '53 & '54 Dodges had 241" Red Ram Hemi's. In '55 the Red Ram went to 270". They increased the size again in '56 up to 315 cubic inches for Dodge.
I'm NOT an expert at all on these, but as I understand it a 392 hemi was never offered in a Dodge, only in Chrysler's and Imperial's. To me it looks like this Coronet is a '54 or possibly a '55, so it would have a 241" or a 270" Red Ram hemi under the hood. Good luck with it, still a cool old engine to have.
After looking at it some more, I changed my mind, it is a 1953 Coronet. So it would have a 241 Red Ram Hemi engine as Redhorse719 originally stated.