At only 650 HP I would just stay with the 727. I would go with a nice reverse pattern manual valve body though and make sure you have a bolt in sprag.
My 727 has seen about 5 seasons of racing in a 3700 pound car and 1 season in the Duster at 3400# both with around 600hp mills.
My new Engine should put out over 800 hp so I'm going to go through and strengthen the 727 a bit.