Running a water "by-pass" in the manifold is worth 10 degrees. Tap the bosses and bring coolant from the back of the block to the front. Jegs and Summit have these kits and they are relatively inexpensive:
http://www.jegs.com/i/JEGS/555/51100/10002/-1
I also agree that timing makes a huge difference. A simple 1 or 2 degrees of timing could be worth a good 10 degress cooler running temp.
Where is the AC condensor located ? If its located dead smack in the middle of the radiator, it may be restricting your air flow. Consider moving it to one side leaving the majority of the radiator surface open for air flow.