[HO455]

I removed a 5 blade non clutch fan and replaced it with a 7 blade clutch fan and I didn't notice any difference in the fan's position relative to the shroud.

On the factory fans for our trucks the pitch is fixed and should not change.

Personally I would source a different water pump pulley before I ever modified a shroud. Especially since the truck is not a factory correct restoration. For me the work involved to make a perfect cut of the shroud would be far more than finding and installing a new pulley.

There is an additional consideration about triming the shroud. That is it would reduce the area of the band around the fan blades. (Indicated by green on photo #1) The engineering of effective air flow through the radiator involves the fan blades rotating inside of a tube. Reduce the length of the tube and reduce the efficiency. How much I don't know but, it must have be a consideration as GM would have reduced or eliminated the band area of every shroud to save pennies per vehicle.

A stamped steel pulley would remove the space indicated in red on photo #2. It looks like that would move the fan back about 3/4" (At least thats what if looks like from my house. )

Good luck and keep us posted.