checked the casting numbers and here is what I found:

engine block 3921970 66-76 292
head 3927763 67-72 74cc chamber
two other numbers on side of head between spark plugs were 7768 and 5060.
Has Mercruiser alum valve cover. Will be installing engine in a '46 1/2 ton and adding electronic ignition from a later 292. Any one with experience in this model? Have installed a pacer independent front end under the truck. Plan on using a 4 speed since I have a 3:08 rear end.