Probably a stupid question, but are you going to use your little J-frame, in any context, as a defensive weapon?
If so, it is not too bright to give up reliability for a slightly lighter double- action trigger pull. I also wouldn't depend on a longer firing pin unless there was a problem with headspace or cartridge head clearance. Should you hit a soft primer the longer pin might pierce it, and then you could have real problems.
The so-called “trigger spring” isn’t exactly that. Besides pushing the trigger forward it also has to rebound the hammer (rotate the hammer backwards after firing a cartridge so the firing pin doesn’t stick out through the breech face) and reset the cylinder stop. Using a reduced rebound slide spring with a full strength hammer spring may upset the timing, and if you tried to pull the trigger before the cylinder stop had reset the result would be a hopelessly jammed action.
You may not understand all this, but I can assure you that the company engineers do. They use the springs they do to insure that under any condition, in any environment, using any primer, the revolver will go BANG! when the trigger is pulled. There is no way you can replace or modify springs – individually or in combination – that won’t affect the reliability that is built into it now.
Admittedly, the trigger pull at a certain weight (for example, 10 to12 pounds) feels heavier in a J-frame then it does in a larger revolver. That because when you downsize the frame the lockwork becomes smaller and the trigger has less leverage to rotate the hammer backwards. Replacing springs won’t change inherent design factors.