you'd need to do some calculations, including exact tire height and rear gear ratio. As long as your highway RPM's are higher than your stall speed, you will not generate excessive heat. I.E. Highway RPM's at 3500, not so much heat. Highway RPM's at 2500, there would be heat caused by slippage in the converter, and more heat generated as RPM's decrease. Install a big trans cooler and go for it!

Shop carefully for your converter. They will need all kinds of precise information to get you the right converter (it must work with your cam selection for optimum results). If you provide them with bad info (or they never ask for detailed info) you will not get the full bang for the buck and may be unsatisfied. The wrong converter can make the car a dog!