Your block usually came with the 283 power pack heads with either a 2 bbl (Impala) or 4 bbl carb (SS). To ID them, look at the front edge, in the middle will be a raised area with a single point in the center. Those are 283 power packs. A 327 head would have the same raised area and have 2 humps instead of a single point (300 and up HP). It wasn't uncommon for somebody to want more power to remove the power pack heads and replace them with 327 double hump (or camel hump) heads and add the 4bbl carb, which is what it looks like somebody did.
Last edited by Cablesmill; 03/04/2016 7:10 AM.
