A simple way to lift your tractor:
Take 1" square steel stock, cut into lengths just longer than the 2 mount holes for your rear end.
I know some have 2 (or even 3) sets of mounts so this exact length may vary.
take a marker, spray paint or other such marking tool, and when the pieces are aligned (1 by 1 that is) mark the holes for drilling.
So given that they're 1" square and usually very strong you can literally lift inch by inch on the rear.
On the front, assuming the swing arm assembly is bolt in and not welded already you can use much the same technique to build lift blocks for the front. I used an old steel meat rack from a grocery store to build mine and they're strong as anything except solid stock...
I can all but promise they'll work if done properly - I've used the same material, same technique to add 4" of lift to a subaru wagon (84 GL, 6" of lift when done) and it held for over 100 thousand miles other than a simple snugging of the bolts from time to time. This of course requires longer bolts... threadlocker and lock washers are strongly advised. I will give pics of what I mean by all this when I get the time.
** Edit - thanks to the wisdom of Mr. Fackler , I noticed I omitted one key point - when lifting in this fashion - extend your front mounts either with the same stock or some flat iron, or make all new ones to reflect the added space between differential and frame/body mount point up front. As I said before, will show examples of this soon!