Stop in for a cup of coffee

I would think the gross HP to drive the 727 and the 9 wouldn't be 'too' huge over what it would take to drive a 904 and 8.75 (or whatever you replace it with). I think the net difference probably isn't huge, unless of course you're looking for every last 1/10 at the dragstrip..
agreed, the 8.75 eats about the same as the ford 9 inch. Now the dana 60 while stronger, eats about 60 horses roughly. Most of your 3 speed autos are gonna eat essentially the same. It's the modern electronic control transmissions that will suffer more power loss, though usually just 5-10 hp.