The old Detroits were good motors, you just had to have them wound tight to get anywhere, and needed a 13 speed minimum, to keep it up in the powerband.
The 60 series pre-emmissions engines are good motors, too. They get a bad rap, but they'll run a million miles, hold up to the rookies running them in the big fleets, and with both set at 470 horse, will pull as well with a 10 speed as a 3406E Cat will with a 13. Personally, I'd get a 4900 IHC with the 466 and Allison auto, with air ride (and a suspension dump valve), and short wheelbase. A longer wheelbase will ride better, but you give up a lot of maneuverability for it. And the suspension dump makes hooking up a gooseneck a lot easier. Less cranking.