Brian you could have a odd block in 262,267,305 and 307 cu. in. engine blocks. There is one more but I very seriously think it could be and that is a 302 cu. in. That engine was used only in some HP. cars. Without the block number on the back left side it is a guess as to what it is. Someone may just put a spare parts engine together. Do you have a VIN. number that you can read clearly? I have the latest ID Guide out and do not see anything on the boss numbers you have posted. I have one more question does your block have a oil filter on the left side.
62Blue
Don
