383 pulleys....

On small blocks with ac the water pump pulley is smaller, so the water pump is overdriven. I think the ratio is 120%, which is about a 5.5 inch pulley I think.

I made a shroud for my cold case radiator out of a slant six one turned upside down. The are lots of threads on shrouds. Search for cold case shroud.

Make sure your fan is half in / half out of the shroud. I learned this the hard way.