I am looking for some info on a set of heads I have. I am rebuilding a 1968 383 and the heads that I got with them have a 250 casting number. I have done some googling and searched through old forums on here and all I know for sure is that they are 1968 383 only as the other big blocks got the 906 that year and that they are open chamber (I have ordered the tools to cc them and will soon). I am going to run them as they came with the engine I bought and they already have 2.14/1.81 valves installed. I am just hoping to find out how they flow and if they respond well to mild port work. Thank you for any info.