Great old 5 screw 22lr

[S&W1954]

I have this wonderful 5 screw, 22 LR, 6 shot, K-frame. I believe it is referred to as a pre-17 model. I will post a pic of the gun. The gun has a very smooth action and shoots great. The DA trigger pull is very tough. Way beyond my reworked 66-1 or other factory S&W's that I have. I suspect the very heavy DA pull is largely due to the springs for the rim fire. I changed the trigger return spring for a 12#'er and that helped some. I would like to lighten it further. I put in one of the Wilson mainsprings and the fail to fire rate was around 4 of 6 which is not acceptable. I have a good light set up in my 66-1 and would like something very close to that pull. I put an oversized hammer nose in my 66-1 from Power Custom to accommodate the light springs. I have thus far been unable to find an oversized firing pin for the pre-17. Currently I am experimenting by partially tightening the main spring screw and test firing until I find a minimum spring tension. Any suggestions (other than take the pull as it is)?