Tight and fun... as a first step, suggest you beef up/tighten up the unibody. Frame connectors, 2"x 2" box section or more, and full welded/gusseted K frame as a start. Torque boxes and boxed LCA's would help also. The car will feel tighter and be able to handle stiffer springs/shocks better... not much point in stiffer springs if the unibody flexes instead. My original 318/auto Challenger drove better with these changes alone. With a BB and 5 speed + stiffer springs/shocks it really drove better.

Big front sway bar definitely. Rear, maybe. Suggest you drive it first and decide on the rear bar.

As far as spring rates, agree knowing the weight would really help. XHD springs sound about right... though I don't know what's out there in A body length springs. As far as T bars... the trend is to go with really big bars. With your goals I'm not sure "really big" is needed though. Significantly more than stock, no doubt. 1" may be more than you need/want with a lighter package and your goals. Maybe 1 step down would be better. Its also a matter of budget... 1" in an A body length really needs high end shocks. .94" HD/Police bars not so much.

Good luck!