Porsche 911 fan kit , which crank pulley ?

[itHaKa]

Hi

i have a Porsche 911 fan kit, with a real 911 fan/shroud on a type 1 engine , the kit came with a 5 inch power pulley, would like to know which pulley size you are using

options i am considering are

Gene Berg steel 1:1 pulley 4-1/4"OD
5 1/4 dry sump pulley
6 inch power pulley
7 inch stock pulley

i would like to try how they affect engine cooling and hp increase/loss