Finally got to the point of adequate cooling with the radiator installation.  Since my last post regarding this topic there have been several changes.  First and foremost, the radiator was reoriented to an approximate 40 degree angle to airflow from the previous flat profile; the air enters bottom and flows through to top, with exit location remaining the same.  With the new angled radiator profile I felt it prudent to add an air bleed connection to its uppermost tank; fortunately there are mounting bosses welded there and was easy to drill a hole into the tank and tap the thread boss for 1/8 pipe.  Now all air/steam bleed lines connect to the bottom of expansion tank.  Also following the discussion with Steve Boese, the Mazda oil cooler was removed and I returned to the dual Fluidyne setup from years ago.

Doing all of the above did not result in immediate results.  Ultimately the air inlet area had to be increased to an equivalent of 9"x7".  This evening the OAT was 72F - at circuit altitude the water temp topped out at 190F with the oil temp at 160F.  Not perfect (I know it can be improved) but is adequate with a 20F buffer before redline.  Time to get some recurrent training on this tail dragger and get comfortable with the machine -- worry about subtle improvements and cleaning up all the ugly fiberglass repairs somewhere down the road ... winter is long, summer is short.
Jeff