seems to me the bushing and pins dont move relitive to each other, only the cylinder bushing rotates
so you dont need clearence for greese, measure the cylinder bushing diameter and work from that
if im right i would just put a bolt through the weldiments and a spacer for the cylinder and weld them in place, weld a lil at a time to control heat and alternate sides when welding
a class 5 or 8 bolt should be a few thausanths under and can be polished a lil more under where the cylinder bushing is
even if you have to drive the bolts into the welded bushings it shouldnt matter, only the cylinder bushing clearance matters
when you use the spacer make sure its atleast .010" longer than the cylinder bushing for grease to seep out the ends for lube