Manual or Auto. valve body??
Well I am bias, like the total control and I would stay manual. But is yours one of the good low band apply manual VB's? If you put in in LOW and say get up to 35 and let of the gas does it engine brake or free wheel?
You can get them in standard and reverse patern, got make sure for your safety it has low band apply. Talk to John at Cope transmission. He will fill you in.
You can of course make a good full auto VB too, but the most controll is a manual.
it is your call like blonde or brunette? Both are great...