325 hemi

More specifically, a 57 Dodge Hemi. 56 Dodge big motor was a 315. Had a 315 hemi in my Dad's 56 Dodge D500.

There were poly versions of both 315s and 325s. Dodge hemi heads will fit these Dodge poly motors.
Years ago a member here shoehorned a early Hemi in a Valiant. I wish I could remember his name here. It looks like it fit pretty nice but I'm sure it wasn't easy.

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That's a Chrysler Hemi. Could be a 331, 354, or 392. Much bigger physically and heavier than a Dodge Hemi.

Here's one that has a 354 Chrysler Hemi. Sorry, don't have any engine pix, but all three sizes were the same size externally.

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Anyway, if a Chrysler Hemi fits an early A, a smaller Dodge Hemi certainly will.