PST doesn't make anything. They just package other parts in kits. Those sway bars are Addco or old Hellwig.
They are fine. The front looks 1". Just go measure it. Fronts E-body and 70 up B-body are sort of no brainer, except getting tubular front bars for the bigger sizes save a lot of weight on the front.
The rear bar you have is 3/4". It's the type that fit under the rear end, U-bolted to the axle tube, and you drill two hole in the frame rail for the end link attachment.
The factory one went over the rear end. There are some companies that make those type (Firm Feel, Super Tuff...). To install a factory type routed rear bar, you have to looseing the rear end U-bolts, install new shock plates, most likely drop the rear spring hanger (E-body rear valence), unbolt driveshaft, thread the sway bar in, hope it doesn't hit your aftermarket exhaust (not likey)...