Or can i reliably get away with just the stock pulley with no fan fins?

Just run a stock pulley, the fan backing plates should create the flow from the fan to cool the alternator. Pay attention to the belt alignment with the lower pulley or the fanbelt can work its way off.

thanks mate, too easy

It's only the new Mexican ones that have the fans, the original ones never did, same setup as gennys had for the last 60 years