On the 226 there is a number cast in on top of the head, it will be 7HA/0HA-226 or 8HA-254 cubic inch. The block number is on the pan rail right below the oil pressure sender/ distributor, It will probably start with 7HA. As I recall it was 50-52 that used the OHA, and earlier they were 7HA. There is a difference in the cams and the oil pump gears the 0HA/7HA each had a different amount of teeth. Also on my 51 F1 there is a serial number on the top of the frame rail next to the fuel pump

Hope this helps
Rod