I did a quick Google Maps search....from Myersdale to Savannah, and it offered two options (in addition to an airline...LOL!!) You can basically go west and take I-77 down or go East and take I-81 south.....or take I-81 down towards Richmond, VA, and then cut over to I-95 for the remainder of the trip south.
A lot will depend on what you want to see. I you are trying to get south as quickly as possible, it looks like western route down I-77 would be the quickest, and may also be the most scenic. I think that is what I would recommend, but I've never taken it, so can't really say for sure. Others will probably have better information.
That sounds like a great truck for the trip...the Hemi should have the power you need. Have a great trip!!