do it the fun way, put a 12" clutch in place of the converter on the TH400!!! Awesome hole shot and can't be out-shifted.
Some years back, my neighbor was one of the lead tranny guys at one of the chevy dealers. He used to make the "clutch flight" conversions in his garage. Did a 454 jeep, drove it once and pushed it home, scared him to death. He was happy when the owner came to get it.