According to the info I've got, everything you said about your engine is correct. As for the "C", it's combined with the "J" to make it "JC", which means it's a 235 c.i., 135 h.p.,1 BC or a 1 BD carb equipped, 8.25:1 comp. ratio, 3 or 4 speed equipped truck engine. The "JB" engine could of had the powerglide behind it. That's what my book says anyway,
Scott