Tell me about these heads - 2658920 66-67 273-318ci

66-67 273 or 318 heads. Closed chamber. No hardened exhaust seats that I can see from the picture. NHRA minimum legal cc is 57.3 In my experience it takes .040 cut to get the largest chamber to that cc. Therefore unmilled chambers should be about 65 to 63 cc. Very nice small port heads. 66 up heads used the standard Mopar small block intake bolts and angle.