What is the best way to get an overdrive auto in a 67 Barracuda?

Building a street car with 400-450 HP, 3.55 gears and a 727. GVOD will make 3/over final drive ratio 2.76
Not going to use the automatic OD feature since this will be a manual shift reverse valve body.
65 MPH @ 3030 RPM in 3rd and 2350 RPM in 3/over. All I need is 1, 2, 3, OD...
not cheap but closest to plug and play so far... retains stock shifter, linkage, console, cross member and no cutting the tunnel.
I'd be surprised if the GV all in cost was more than a couple hundred more than buying everything to do the 200R4 and mods. It would be different if I did not already have a 727 trans and Cheetah Reverse Valve body. Will look for your write up though.