The Jetfire block is different than a 215 used in any other body style. The main bearing cap bolt holes were drilled and threaded 9/32″ deeper. The main bearing cap bolts are 9/32″ longer and have 12 point heads. The pistons used were only used in ’62 & ’63 Jetfire’s and ’63 4bbl carb cars. The main bearings were “Marine-400” bearings and were unique to the Jetfire cars. The heads and valves were different too, but you only asked about the block. You can make a Jetfire block from a non-Jetfire block by drilling the main cap bolt holes deeper and threading them to fit the longer Jetfire bolts. Functionally, it will work, but as Eric states, the block identification will be incorrect. Just depends on what outcome you want?