Lots of good ideas in here, Tim. Here are some of my own ideas and my take on some of the suggestions offered here.
Regearing -- agreed this is likely to make the most difference as it will reduce strain on the drivetrain = less heat generation. Less torque converter slipping, engine running at higher RPMs and more reasonable loads rather than being bogged down all the time.
Electric fans -- A pusher fan in the front of your radiator can help a good deal. My little 1000cfm one certainly does. I would NOT change your mechanical fan to a primary electric fan. I have also personally had bad experiences with this approach.
Mechanical fan -- I know your fan clutch is new, but have you actually confirmed its operating correctly? It is also possible to change the viscosity of the fan's silicone oil to make it hook up more. Reading these
two links it sounds like the factory units are sometimes underfilled with silicone oil as well!
Coolant -- Good idea to try a higher water % in your coolant mix as water is a much better heat transfer fluid than ethylene glycol. Redline's water wetter or similar is a strong surfactant and helps the coolant reject heat into the radiator more quickly but I'd leave this as a last resort.
Radiator -- Sounds like a lot of people are suggesting an upgraded radiator. Makes sense to me.