running hot

[jetfixr]

I recently bought a 70 c10. I took it out for the maiden voyage today just to make sure everything works ok. At highway speeds it was running about 195-205, in light traffic 210 and climbing. I would like to see it run 20 degrees cooler, I noticed in the glove box there was a empty box for a 185 degree t-stat. So I am assuming it has a 185 degree t-stat in it. So I am trying to figure out why she is runnin' so hot. One thing I did notice was that the fan shroud had approximately a 20 inch opening. While there is a 7 bladed steel fan that is only 15 inches in diameter. Is that normal? Also the fan is not centered in the shroud there is about 1 inch clearance on top and about 4 inches clearance on the bottom. Could this be the reason for the problem? The radiator is a 3 core but I was really driving easy so I wouldn't figure it should have a hard time keeping up.