I have a 5 1/4" Ford steel double groove water pump pulley that will fit a 302. The bolt hole spacing is the same as stock Bronco. I also have some that are 5 3/4" in diameter advertised in the Parts For Sale classified.
The 5 3/4" is slightly smaller than stock. The 5 1/4" is the smallest Ford pulley that I have seen in the yards.