For a good torquey drivetrain with fi and od, think Magnum and a518 trans. Should fit the c body without too much hassle. Running donor truck or van can be found cheap.

Should be able to get mid teens in a c body.

Personally, I think most folks short change the abilities of most late 60s through 70's cars. They are actually pretty competent drivers. No not as razor sharp as some newer stuff but at normal speeds they do just fine. Sway bars and good shocks are the minimum but also the maximum.