Do you see much trigger creep? You shouldn't as Shadows come with shorter-than-usual hammer hooks. If you still wanna install comp. hammer, you are kinda 50/50, some require disconnector fitting while others don't. Safety-to-sear fitting will be required thou as comp hammer bed is higher and thus rotates sear forward and pushes sear against safety (left). Some people like fitting sear to safety, I fit safety to sear, it's easier and quicker and does same thing.
For softer hand loads you can use 11# to 14# recoil spring, one that will allow brass to eject 6-10 feet away from you, not dropping brass onto your feet or launching it to another Province. Main spring can be as low as 13# but you may experience ocassional light strike, especially on new gun or/and with CCI primers; 15# is safe bet. You can go with 13# main and extended firing pin for reliable ignition too.