I have picked up some LJ Torana caster rods - not exactly sure if they fit the same as they did when I had my 510 but will find out. On my 510 I had the LJ rods threads machined further back for more adjustment - though cutting threads is not the best engineering solution... The added caster made a huge difference to handling.
Doing some reading and have short listed some Kings KDFL-01 120-220lb progressive rate springs if they fit the 810 struts. They are stated to fit a 180b/610. I'm probably leaning towards using offset standard strut tops as I'm not keen on running without sealed thrust bearings, and the aftermarket ones are rather expensive.