Im not sure but I have a set of pistons and head from a 77 matic. I compared the pistons to some k pistons and they look just the same, I measured them up and all the measurements were the same too. I compared the head to a 76 k head and the combustion chamber is noticeable bigger on the matic head. but I dont have a 77 k head to compare the same year model heads so the 77k head may be the same as the 77 a head.