Very good write-up with picture. Would like to see further write-ups as you proceed.
Interesting steel selection by Pedersoli.

I had thought that Pedersoli brazed the back half of the barrels and then soldered the front half which allowed them to fine tune regulation. From your writeup, it appears that Pedersoli brazed the full length of the barrels together. If I read that correctly, that would prevent them from fine tuning the regulation.

I shot my Pedersoli 58 cal DR with Hornady Great Plains 505 gr conical bullets driven by 120 grs of 2F. It was a fun gun to shoot, strong push for recoil but the accuracy probably was more paper plate size. I questioned whether the accuracy was due to lack of fine regulation.

Thanks for your write-up.