I think you may be expecting too much from the original rad - for starters it wasn't designed to hold any pressure at all, or 3# at most, with a 16# cap at 250 it's likely to be getting close to 16# ... the trans cooler and condenser will not only be blocking air flow, but adding a lot of heat to that air, the trans will get as hot as the engine pretty quick - and positioning of those as well as of the fan will change things
again, spot check actual temperatures everywhere with a digital thermometer
Bill
