Good luck finding a correct I244 block. I have 2 I244s both have had engines replaced one has F226 out of a 44-6 - other F245 out of God knows what - one had cracked block which I don't think I have - other I have block but in pieces unknown condition.
Best bet is probably a Continental F244 or F245 which were used on lots of Industrial applications such as Air Compressors for jack-hammers. F244 correct vintage also used on some Combines - Oliver??
Would be interested in comparing notes on I244 - what is your serial number? USAF, USN, or USA Corps of Engr? Cab? Magnet?