Rad and fan replacing

Instead of starting another topic, I figure this is a good place for my questions.

The 1973 Dart Sport we're fixing up has a 19" radiator. I think maybe it's a replacement radiator. I has only the number 20446 and a Pentastar on it. Is this a basic Chrysler replacement rad or what? It has a hole at the top where some smog control device is installed, but not hooked up.

The car is a 318 2 barrel, no A/C. What would the correct radiator be for this car? Shouldn't it have a 22" radiator?

My Galen Govier white book shows either a 19" or 26" rad as being correct, but only shows a 22" rad for a 225 slant six motor, not the 318. This seems screwed up to me! How do I know what it should have or what number it should have?