Great points Wally. By equalizing the temps in the way I mentioned, you are right ... they won't nessesarily be cooler (hotter I would think) but they may be even
The airflow must be directed from top to bottom as you have mentioned. Check out Remmele's website under his pictures section and look at the pic of the inside of his shroud ... it is quite flat right behind the fan and it looks like this dumps the air vertically between the cylinders.
I'm sure this shroud uses the 964 setup and with the vanes you have shown on the 964 fan, you are much further ahead than I, I would think, down the road to improving cooling.
Perhaps a 964 fan setup is in my future ?
Sandeep