DatsunDylan

Nissan out sourced their parts, it's a Nissan factory part not made in a Nissan factory. A very common one, is AMPCO, Atsugi Motor Parts Company. They were one of the companies licensed by Nissan to make parts including L24 pistons, water and fuel pumps, and struts. If you look at your pistons they will say AMPCO or Atsugi on them, not made by Nissan, made for them. So I don't have trouble believing Torco was one of those companies.

Nissan sourced their parts out to other manufacturers, they didn't make everything in house. Ampco made the struts and some fuel pumps like on the Datsun 620, they put their customers part numbers on them.

You could always try and find the factory rally springs, this guy went into immense detail about the factory Torco options with spring rates and diagrams. If the factory rally setup could survive the EAS it can handle whatever you plan to do. http://www.jdmjunkies.ch/wordpress/2017-01-19/240z-the-ultimate-guide-to-factory-suspension-and-options/

Some EAS legends in 1974 before the race i think, im pretty sure they got some serious damage during the event. Far right is a car I didn't know existed until recently, #35. I can tell because it was the only car to have red stripes on its frog eye hood lights. 260z driven by Zully Remtulla and co-driven by Nizar Jivani.