I ran a 64.5/71/.83 with a 80/96/1.10 compound setup in my LMM for a while, and it was one of the best driving compound trucks I ever drove. Extremely responsive and quick to light, but it definitely choked out up top. Guys have made 1k with the standard 366/480 compound setup before, but I can tell you it is way less responsive than what you currently have and will only be slightly better than the S400 combo Richard recommended above. For a truck that is used for towing and daily driving, I think you would be better off sticking with what you have and maybe upgrading to a 68 in the valley and a 485 for the atmo charger. I know a few guys have run that combo and been very happy with it. I'm not a huge fan of big VGTs, but they do have their place. If that's the route you go, you need to have the tuning spot on to get it to run and drive as good as possible. Fixed setups seem to be a little more forgiving.