I have a JARD in a large pin sear block Colt. The sear block had to come out. No problem for my gunsmith with milling machine and I have seen it done with a Dremel. It took a lot more work to install than the directions implied, the adjusting screw holes were distorted, the metal too hard to retap, so he had to do some screw mods to make it work. I am sure glad I took it to a pro's shop instead of trying to DIY. I was rewarded with a 2.25lb trigger pull nearly as crisp as a bolt action. But this is only a target rifle.
For home defense (Where do you live that a rifle is suitable for home defense?) I would want a polished up stock trigger or a hard tested 3-gun installation.