Despite its slightly larger size, your Road Runner will be very close in total weight and very similar in weight distribution as your Cuda. You may have 1-2% more front weight, but that's about it.


Some basic combos I've calculated for my '74 E, which is easily as heavy or more than your '70 B;

.96 t-bar with 1.25 sway or 1.18 t-bar with 1.125 sway for front combo.

160# XHD leafs with no sway bar or 120# oval track springs with .75 frame hung sway bar for the rear combo. Either of these match with either of the above front combos.

Obviously the big change in t-bar sizes can have a big impact on ride quality on public roads that may or may not be in good condition. Since I'm leaning more towards autocross capability than street comfort, I opted for the heavier t-bars and actually have stepped up to 1.22 t-bar and a .95 axle hung rear sway bar. These also were for my small block/ 4 speed set up. A heavier big block/auto combo would most likely do better to keep front t-bar sizes in the 1"+ range.