Do the engine block colors signify anything?

I've seen slant six engine blocks in many colors, do they mean anything? I'm asking because I'm trying to find out what the correct block color was for a 1971 slant six 225.

Chrysler Blue is correct for a US- or Canada-market '71 Slant-6 in a passenger car, regardless of whether it's a 198 or a 225.

More detailed info on block-head paints in various years and markets here, and engine accessories and tinware here.

The Mopar Performance engine paint is of crummy quality (and the red is a poor match for the factory-applied red, at least on Slant-6s). If you're going to the trouble, pick a better brand. Bill Hirsch's stuff is probably the best on the market, but it's expensive and you'd have to get it put into spray cans. Krylon or Dupli-Color is a better-than-MP option you can pick up easily.