I realize this thread is quite old, but I felt I had to contribute a few things:
1) The JCW lowering blocks are 'okay', but they do NOT anchor the new lower shock mount to the swingarm! The result of this is a bit of clatter and "shock float" on rough roads. I had a set of lowering blocks from the 80s that affixed at both the original shock mount and with a longer bolt through the swingarm adjuster stop plates. If you can find a way to use both of these to hold the blocks down, so much the better. (BTW- those lowering blocks I had came with my bike, and when I sold them on ebay, they fetched $158!! Some people will buy anything with the word "chopper" on it...

)
2) There are several places that sell lowering SHOCKS as well. Two come to mind:
http://www.lowridersbysummers.com , and
http://www.crc2onlinecatalog.com (enter the site, then click on "Chopper Stuff" at the bottom of the left frame, then go to the third page, all the way at the bottom. You could go directly to
http://www.crc2onlinecatalog.com/chopper3.htm , but you can't get back to the main site then.) These will give you 2" of lowering without changing the angle of your shocks, which some say has contributed to bent shocks as they are now taking a slight side load instead of a purely linear load.
3) At the cost of authenticity, you could modify the frame to fit a curved pan seat like are found on the Harley FXST and others. The downside to this is having to find a new mounting place for the battery, and switching to pod filters, as the factory airbox will no longer fit. Not as hard as it sounds, but traumatic to someone who doesn't want to 'chop' their bike.
I suppose you could combine the lowering blocks and the lowering shocks, but then your front end would be 4" higher than the back, which will definitely impart some weird handling. You could slip the forks up 4", or even just 2", but then they would hit your handlebars. The only way around THAT would be to switch to clipons, or get some 'dogbone risers' as seen here:
http://cgi.ebay.com/ebaymotors/4-Dog-Bone-Risers-7-8-Kawasaki-Chopper-Motorcycle_W0QQcmdZViewItemQQcategoryZ34284QQitemZ4607109852QQrdZ1QQsspagenameZWDVWThe only issue THEN is making sure your fork legs don't hit the lower triple clamp!
Anyway, don't know if this is still a concern, but thought I'd put up my thoughts anyway.