Thanks to all for your help and information!
Looks like the engine block was cast in Flint, Michigan on February 5th, 1960/61/62 (conflicting websites abound) and that its intended role was "Standard" (as designated by the 'A' serial number suffix).
So this little truck rolled along for almost a decade and then had its original 216 replaced by a plain jane 235.
Excellent nostalgia!
