Nobody makes one for commercial sale, although some have tried. The only succesful attempt caused such a porformance increase, that the trans went POOF.
The best you can do is keep it cool. The 180° thermostat and Trans cooler are the best ways to do it. Other than that, like 94 said, just keep an eye on the coolant level. Should the unthinkable happen (and it may have already before you owned the car) you'll be prepared. There'* a Techinfo article on preparing for and replacing the upper on the Vin K engine.
As far as the ease of the thermostat swap.......Lilpooky is our youngest member at age 13. She has succesfully changed a thermostat entirely on her own, without my guiding hands touching a single tool or part