I've installed the SPAX shocks. I'm still using the older version (just 14 clicks, so slightly coarser adjustment). They are not double adjustable, but the last few clicks in the range effect both compression and rebound.

The G480 & G481 shocks are designed for Australian valiants and need some minor mods to fit the US & UK A-bodies. Front shocks need the bushing sleeve opened up very slightly with a drill or reamer. Also SPAX ran out of bushings for the rear shocks, so you need to install your own bushings now. (this was some years back, situation may be different now).

For the rear shock bushings, I used polyurethane Chrysler 5/8" Shock Bushing (Energy Suspension #9-8112G). The 11/16" inner diameter was not available. However all of the other dimensions are correct, so its "just" a matter of drilling out the center. Although easier than drilling rubber, the bit still wants to tear rather than cut the soft material. Freezing helps make it stiffer. After drilling, I cut the bushings in half with an Xacto razor saw and a sharp utility knife. By making two halves, the bushing does not need to pressed in.

My old What's it Got? - Suspension webpage and more on Dave's Goldfish Page, halfway down. Lame Horse Racing - Goldfish He used a different bushing with success.