i am not a suspension expert but cutting out leaf spring mounts and welding in new mounting points probably is not that big a deal if you are a pretty good metal worker and fabricator. i think I would be more worried that the spring would be too stiff. full size blazer weighs a lot more than a luv. especial the rear end. i think you are setting yourself up for a very stiff ride. You also might have to do some adjusting on axel mounts and maybe drive shaft also.
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Did a v8 conversion in 1981 on my '76 luv
Current Fleet
#1 1980 Black 2wd, #2 1980 Blue 2wd, #3 1980 Black 4x4 #4 1980 black 2wd Long bed #5 1979 black 4x4 #6 1977 red 2WD
pics
http://s137.photobucket.com/albums/q223/gs11x/