Thanks to all those who responded with ideas on getting the temps down. 

Currently pursuing a thorough cleaning of the cooler and engine per Bob
Hoover's suggestion. Thus far a quickie job on the cooler has brought temps
down about 20 degrees to the 210 to 230 range and pressure is boosted to 30 +
(55-60 mph).

Following the big scrub, I'll try Joel's idea of switching to Kendall oil.
According to Joel, my engine compartment will be able to do double duty as a
beer cooler afterward.

Thanks,

Weston