Here is the plan, I am removing the plastic tanks and building new ones with aluminum.

The new tanks will be made to make the radiator into a two pass, BUT, not the way everyone else does it. 

I gotta be differant. I am using the back half as the first pass and the front as the second pass.

This should make it the most efficient.

As the water flows through the back half it is at it's hottest and will be cooled down some. Then it will flow through the front where the coolest air is and be cooled down even more.

Even as the air is heated up from the 2nd pass which is in the front, it will not be as hot as the water in the back 1st pass, so it will still be able to remove heat.

This same principle is used in refrigeration so it should work here as well.