old books claim 10-1 comp, but it really isnt. See if you have 906 casting heads on it and if you can tell if the head gaskets are steel shim or composite. 6pk pistons does help the CR but you just dont know what you have untill you take it apart. If the pistons are not flush with the deck and down in the hole, it will not be a 10-1 engine, but you still could make tq and resonable power. 6 9 i believe means june 1969