Drive Train Upgrade Suggestions

Oh oh, You didn't give a budget. My thoughts would be a 5.7 Hemi drivetrain to an 8 3/4 rear, (you likely have a 7 1/4 rear in there now). Stock 8 3/4 rear can handle 275/ 40R17 which is a fair bit of wheel without customization. Make sure you have large bolt pattern axle in the 8 3/4 for better wheel options. Small bolt pattern wheels are scarce and expensive.

Budget is $25K for everything except the acquisition of the car (ie. body-off paint, front-end suspension, reupholster interior, replacement bucket seats, A/C, power steering, wheels/tires, misc.). I could cover another $5000 without facing a divorce. From what I'm reading from everyone since posting this, I'm gravitating away from sinking costs into hi-perf /6 upgrades and likely to go the 318 route to stick with the same K-bracket. Were you able to fit 275s into the rear without modifications?