Really mild cam only slightly hotter than stock.
Something with an advertised stall speed of 2800rpm should suit you. Diameter does not matter.
TCI are cheap and very popular. But many transmission repair shops make a lot of money from transmissions that have used TCI converters so steer clear of them. Mine lasted about 2000 miles and killed my crank as well as the trans.
I currently use a TCS converter. More money but you get what you pay for.
http://tcsproducts.com/