Firstly the heads found on the 383, 400 and 440 were all interchangeable in other words the 906, 902, 452, 915 (and there a few more) heads will fit any of the 3 engines mentioned. None of them were specific to the 383's, only depended on the year and HP of the 383. Price Example, bare/stripped 906's for $100 each up here, complete with everything and ported $1200 each.