As per OKFC05, I would use the #2 Wolff mainspring and an 11 or 12# rebound. You will want to use #222 (now grade H) low strength Loctite on the screw. It will be adjustable, but stay where you put it. I use a #8-32 x 1/2" long socket set screw for the strain screw. I drill a small access hole in the grips so I can tweak it easily if needed.
Make sure your firing pin is at least .495 long, longer is maybe better. I prefer .500 to .505. Most factory ones are too short. One that is short takes a harder hammer fall to be reliable.
My way, my opinion. Doesn't mean anyone else is wrong, we all have our favorite way of doing things.