I have rebuilt several C-6's and the best kit that I have come across is the one from JW Performance (the makers of the Ultra Bell. TCI also makes a good C-6 kit that comes with a shift kit (forward pattern)
The JW was the most complete. It had every possible bushing and lot's of extra gaskets for minor changes made to the C-6 through the years. It doesn't come with a shift kit though. I had good luck with a TCI forward pattern street strip valve body and the changed to an old B & M full manual reverse pattern (no longer made) that I bought off the web.
For the I vote for PTC. Performance Torque Converters. Located in Muscle Shoals, Alabama. (NW corner of the state)
They have been around about 5 years. Spends next to nothing on advertising. All word of mouth. Results create sales. You can go to just about any track in the Southeast and you will see more of their converters than any other.
It is owned by Kenny Ford. Kenny worked for TCI for like 20 years, back when they made the good stuff. When TCI was bought out by Federal Mogul a few years ago he opened his own business. I have been there and stood and watched while they freshened my converter on the spot. Small operation. About 12 guys doing converters, 2 on transmissions. I was totally impressed. I have had two of his converters. One for a C-6, one for my current glide. I have had others brands over the years and his are the only ones that stall EXACTLY where he said they would. I wanted 5400 rpm in my custom 8" and that's where it's at.
They have converters all the way from an RV to a 7" race. I have a 8" custom. Only $645 compared to the $800 that Art Carr wanted for the SAME thing. The reason I say same thing is that all the converter comapnies get their internal parts from about
3 suppliers. A buddy of mine has a PTC 10" race converter ($375) in his 69 Mustang with hyd cam, iron headed 460, C-6, 4.56 gears. It runs dead consistent 7.0's 1/8 mile, 96 mph with 1.52-53 60 ft times.
Call them, speak to Kenny, you'll be glad you did. They have a small websitewith a basic product list and price list: http://www.ptcrace.com/