Wow with all that in there I'm surprised it worked at all. Looking at your pics a good clean would have made it function and feel better. Go easy with that Dremel it's easy to get carried away then it could be new part time. Have fun working on it and enjoy your results. Let us know how it feels shooting it after all the work you've done.
There are Tanfoglios in CA they just don't come up that often and if their near me and a good deal I try to snap them up. Right now I have seven and enjoy each one. As for the FP spring I haven't changed any of mine even with a lighter hammer spring and all I shoot is factory ammo and have had no problems. Best thing to do is while you're waiting for the spring go out and test it as is and see if it works. As for polishing there's really not much to do that shooting it wouldn't take care of. What Tanfogilo do you have? Here's a couple of my builds.
It looks like they all are Cajun Gun Works parts. You have the race hammer, 85c trigger, CGW Trigger pin and one of two different types of disconnector CGW sells. FP could also be different because certain discos require a different FP setup.
I have one like it but made by Cajun gun works for CZ pistols. I tried it in one of my SP01s and didn't like it. I wanted it for the shorter reach of the double action but when firing the gun my finger would creep downward and get pinched between the trigger and guard. You would think even with the slight curve your finger would stay in place but in my case it did not. Funny thing is I have a few flat trigger SA CZs and do not have this problem with them.
If you have any of the full size 75 guns or even a SP01 you can get a Bullshadow upper and put it on the frame. I would call CZ Custom first to make sure it doesn't need any machining to fit the frame. I picked up a used Bullshadow upper and have had it on a 75b SA and a SP01 frame and only had to lightly sand where the recoil system goes into for it to work in the SP01 frame. It now resides on my 97b frame and I love shooting it.
Sounds like problem solved good deal. Ultimase thank you I didn't know each side of that spring has a different adjustment. Now I have to check all my CZs.
How is the reset on your trigger, is it real positive or can you barely tell it resets? Next time you get a dead trigger push or pull the trigger forward to see if it resets. If it does you need to adjust the set screw for the reset in a little more so the trigger can reset.