Mtnman, Welcome! From 59 till 65 FE engines were painted black. Aircleaners and valve covers were red, green, blue and gold through the years. Starting in 66 engines were dark blue then 69 and on a lighter blue. I think some early (pre 58) truck engines might have been red as I remember. Anyone could have painted them any color. As far as it meaning anything special? Don't know but depending on what heads and intake they might be something nice.

Kapp, Welcome also! Your C3 block is a 63. Post the entire casting number and we will tell you what it is. C3AE-6015-? with the last letter after the 6015 as the indentifier. 63 still had normal casting numbers and not generic like the later years. 352 was on most blocks to tell it was the FE family and does not always mean it's a 352. Later blocks have the reverse 105 and some nothing at all. Funny I have a 63 406 and the block does not have the 352 marking. Just the casting number, date code and the HP markings. Post the head numbers if you can also. They are between the center two spark plugs.

G.