I think I have a standard 18 and there's available the 19.25" for my 69 Road Runner. Anyone try anything bigger and what did you get it out of?

There was a 19+ (around 19 3/4) 7 blade fan with cupped tips on the BB Cordoba's. If you need to move a lot of air you might try one of those. I got one on a core engine but didn't need it.

I've never switched fans on anything, but do know from experience that a good water pump (aka Edelbrock) sure makes a difference.

If I were in the market for a larger mopar fan and wasn't concerned with it being 100% stock looking I would find something off a 70's or 80's van or pickup. Just from memory the last time I went to the pick-n-pull some of the mopar trucks and vans had jumbo sized fans with rather large curved blades on them. They looked a whole lot more efficient than any of the fixed blade 60's fans for that's for sure.

I have the correct fan for my 70 dart, but am thinking that one of those junkyard fans would pull more air. So long as it fits in the shroud......