Stew Wilkins sells the Commodore Bilsteins re-valved to suit Datsun rally cars - though they are around $850 (front pair). Standard Commo Bilsteins are around $600. Then there is the strut tube mods etc so quite a bit of money and work. I think he also re-valves the Commo wagon rear shocks to suit also, though would have to check. Rears around $400 standard, $650 re-valved. BTW: Commodore Bilsteins have a comparatively large piston size for better heat soak.
The KYB combo is around $500 total, Z31 front, mono tube rear, rather palletable price. As always, the danger is building the worlds cheapest 120Y into the most expensive! (Car cost $38, it was actually $40 but I found $2 in the car).
Also got some disappointing news - my 40mm Dellorto's I bought very very cheap from an old Alfa enthusiast work mate are DHLA40"G" marked - G as in emission carb and a right royal pain to do anything with... They might be up for sale soon. Good for a Sud and that's about it.