I concur with PontiacJim. Continental used to provide what was called "The Jim Hand Converter". The reason was that Jim Hand used it in his 4200 pound station wagon. He got it into the mid 11's with a 455 that used factory parts. IIRC it is a 13" that flash stalls to about 3000, but it is tight under light loads. The last owner of Continental died and if it is still in business it would be under a different name. The old address and phone numbers were 730 Centinela Ave, Inglewood CA 310-674-1072. Be aware that stall speeds are proportional to engine torque. One that stalls at 3000 in a 455 would stall at about 2300 in a 350.