Start with trying a 180 degree t-stat. Check the clutch fan for sure and about 1.5" should sit outside the shroud.

Have you the rad filler pieces in and the 400 air baffles?

Have you checked your water pump? could be rotted away...check for flow but there are a lot of good threads on W/P's here as well and how to increase the flow and efficiency.

Late and tired tonight but I'm sure others will help as well.

Lots of these little things all add up to a cool running engine...