Perhaps this is not a 320 but a 40 - added a couple photos if anyone can tell. According to jd40.com, the engine number would fit into the 2/8/1954 category.
Also, I might be mistaken on the sleeves. When I looked inside the block it seemed like it but with the pistons out I buffed an area on the top of the block and it looks to be stock. The cylinder casting must run long inward a bit on these.
I'm guessing either there is not much time on the engine or these were pretty long lasting. I find no ridge, the cylinder looks to be right at 4.00 bore, the main a hair under 2.400 and the rod journal a hair under 2.5. Too bad it was so rusted up inside the engine - the rest of the tractor seems great.