Any guidance on my 1970 Duster plans

I'm a fan of the '73-76 spool mount stuff.

Like @Kendog 170 said, they don't break.

Plus the sway bar is a better design with it's shorter arms, better mounting and it doesn't interfere with wide tires or the later brakes. There is an aftermarket swaybar for the biscuit mount k-frames that uses the later LCA, but it still has limitations.

Note that the '68-72 steering works with the spool mount k-frame, you just have to swap (or keep) the idler, pitman and centerlink all together. The later parts have the benefit of working better with the G3 swap, but it doesn't matter with a smallblock.