what trans to use for road race?

I have been road-racing since 1960, and the small block Chrysler in an A-body works quite well. There are two brothers racing an A-body Cuda and Dart with the 4-speed and 273" in the Philly area in SCCA competition. There was an automatic Cuda permitted in the original Trans Am racing forty years ago, but the driver was handicapped. Many tracks have PDY events (run what you brung) that permit automatics, and the Lemons Series permit them as well. Using a heavy big block will never work well as the handling is miserable; we had a fellow show up in a '70 R/T Challenger with the 440 at Summit Point Raceway years ago, and the car was an ill-handling beast. A 340" block with aluminum heads combined with an after market aluminum close ratio 5-speed manual gearbox in an A-body would be a killer in road-racing and autocross.