FWIW, I can tell you my Dad's (now my) late 63 Galaxie 500 had a Ford service block replacement (390) installed in 1972. It was definitely through Ford and the block was painted green (sort of a lime green). It included heads with have a C8xx-xxxx code (I forget the specifics) and one of these days I need to crawl underneath and look for any dating information on the main block. It's only run another 100,000 miles after the first one broke at 121K. Rumor has it my dad's sons were blamed when he was encouraged to "jump on it, Dad" when some lifter snapped...