Till we get there with that pin, one could carefully hone any dings off the knuckle and lightly lube it for the least friction. I could see an extension on your pin and a nut on the outside for support. I would not overly polish the outside of the knuckle or the corresponding bore in the receiver other wise slop could be introduced that could have a negative effect on pull consistency.

Nicely detailed photos by the way!

On spring mods do them carefully, you can remove so much tension that the trigger will not return if partially pulled. I was pig hunting at night and pulled the trigger on my Enfield, to the point it almost discharged. The pig moved and I took my finger off and was pushing on the safety causing it to discharge. Quite unsettling besides spooking the pigs. Many hardware stores will have an assortment of compression springs, probably once you find a likely candidate the piece will be long enough to make many springs.

Grammar and spelling mostly corrected. :-)