Not in my opinion. But, if you can't find "the stuff" (used) to convert the front to big pattern disk brakes, tubular uppers might be a way to go. Youll still need spindles, of course.
Somewhere on the vast darkness of the www. there's an article on limiting pump pressure to improve feel of a factory PS box setup.
I'm a very low buck guy. I improved the heck out of the rear suspension on mine, I junked out a couple 73/4 a Duster/ Demon for parts. Took my factory rear spring pack apart, took one of the 73/4 packs apart, and put one pack back together (on pair I mean) using the longest leaves from both packs, and as I recall, used 1 more leaf than original, and of course it's a longer leaf.
You can buy spring center bolts from a "real" fasteners store or a spring and brake outfit.
Just putting better tires than "we" had in the 70's should help some
