those lowering blocks make the bike ride rough, it increases the effective spring force.
I lowered the shocks on my 750, took the shocks apart then chucked them up in the lathe, brought the tailstock up, and measured free hieght, then broke out the torch and heated the very end coils up while cranking in on the tailstock till it had a free height an inch lower, let them cool down then put the shocks back togetherand tried them out, much nicer, could hold it comfortably at a light. did it because was going to pick up a set of 11" shocks, but that worked out so well I've pushed the new shocks to 'maybe some day' end of my list.
could likely do it on a drill press just as easily
my shocks have the chrome sleeves so I wasn't worried about discoloring the springs, but it turned out they didn't discolor, been riding 3 years now since I shortened them and haven't run into any issues.
I wouldn't go much more than an inch without shortening the shaft on them, otherwise you may bottom them out
ken.