This time, I agree with Bryon.
The hand stamped 'MO' code is NOT a guarantee that it's a 302. To be *more sure* that it's a warranty replacement 302 short block, you'd have to disassemble at least enough to verify the internal parts are 'factory 302' parts! ie. crank at least, and the rods, and pistons if you took it down that far. If it was an unmolested 302 short block CE engine it would also have the factory numbered 302 camshaft. If the block has all that, it would provide good confidence that the CE engine was provided to replace a 'blown up' 302 under warranty.
Without confirming the internal parts, your CE engine could be a replacement 350 block that someone (later) stamped with the 302 assembly codes to 'fool' others.