My roadster pickup is not channeled, so fortunately I don't have a driveshaft or transmission hump to contend with. I have built channeled T's in the past, and the seats can be a real misery. Unless you want your head stuck up above the windshield, or a really tall goofy looking windshield, you have to get the seats down low in the cockpit. One way is to custom build the frame so that the framerails in the seat area closely follow the outer contour of the body, and fabricate a driveshaft tunnel from heavy ga. sheet metal (not less than #14 gauge) that is only about 5/8" larger in radius than the driveshaft, then tuck the seat down into a recessed pan which drops the floor down between the framerail and the driveshaft tunnel. This still ends up being a compromise, and if you have a big butt like me, you are never going to get too comfortable in a T seat.