As far aluminum pump goes, I couldnt tell ya, I've never ran anything but a aluminum high flow since day one on this combo.
I'm sure it will make a differnce though, I've read where they have really helped others, it's worth a shot, and it dam sure cant hurt.
You never did say if you checked for air flow obstructions going to the rad.
On hot race/street motors the radiator really needs alot of clean air.
Have you tried any cooling additives?
Are you running a 50/50 water/ antifreze mixture?
Straight water will run cooler, then you can add some red line water wetter or something like that for their anti-corrision properties.
They claim 20/30 degrees difference.
I personally seen a 15degree change with the boys mustang.
Goodluck, Cp