I bought the Stagg struts to get through an inspection.   I like them so far!  I believe I have some sort of aftermarket spring, as the suspension is very stiff, but much more compliant then the old hardware that was in there before.

I got them here for my 280.  the 3012 and 3013. I had to wait awhile for the rears that were on back order. Took about 3 months.

 

http://thmotorsports.com/tokico/tokico-shocks-hp-series/hz3012/i-526535.aspx

There are other shock options for the S30.  Bilstein P30, KYB, Monroe, Koni,...  Tokico had stopped manufacturing shocks for slow selling applications back in 2011.  The pipeline for the S30, S130 and many, many other cars was drying up in 2012.  I doubt they will start back up for old Datsuns.  Talked with the head guy at Tokico USA in 2011 and they sold over 110 shocks for Fox body Mustang for every 1 shock they sold for ANY Datsun. 

I thought Koni stop making shocks for the Z a long time ago. Guess I was wrong.

We should have had more of the stock 240Z spring sets made. It's been at least ten years ago, but we had stock US springs made and Euro springs (15% stiffer) made because Motorsport no longer carried them. We had initial orders of ten sets, with an extra 30 sets bought and sold by Courtesy Nissan. After that no more were made. Someone could contact Courtesy and see if they remember the company. I forget now the name of the company I contacted to make them. I found them on the Web and they made automotive springs.

I was referring to the Koni universal inserts (8610s, 8611s) but I do keep hearing of people who are able to purchase the old Special D Konis.

How about McAllister Industries' Chamberlain coil spring mfg in Surrey, British Columbia?...

 

www.mcallisterind.com/chamberlain-spring-services.html

 

They offer prototyping services and low-volume production runs.  Not sure about their pricing structure, but probably attractive in light of the current state of affairs with our Canadian dollar.

I would be down for a set of euro springs for sure.