Any companies selling complete small block overdrive transmission assembles?

I have an a500 sitting here in the garage that's getting rebuilt soon, I'm debating on whether I want to go that route, whether I want to put the 3rd pedal and a hole in the floor for the 833od that I also have here, or whether to just leave the existing 727 alone
My project is different though. It's a D150 with a warmed over/6.
I do have the adapter plate as well, to be able to put the small block bellhousing pattern a500 in behind the/6.