Strange, in Australia we can get most of the consumable parts (shocks, points, gaskets, brakes, etc) even for my 1977 first gen and 1980 second gen.
Koni and Bilstein will normally make up any shock absorber that you care to specify if you are prepared to wait.
Koni has a standard shock listed at
http://www.koni.com/index.php?id=254
You can get it revalved for extra cost or if you talk to the supplier they might be able to find another standard one with the same casing but stiffer valving.
Read the web site for how they specify shock settings.
Bilstein has a rear shock listed at
http://www.heasmans.com.au/new_site2...stein%20B6.pdf
(RA43 is same shock as RA23 and RA55).
Check on the web for any other favourite shock manufacturers.
- Stepho