Welcome to the forum Jim. I think particularly in this section you will find SAKs that replace the liners with steel, the scales with Ti, Al, and steel. I personally have used steel rod for some of my mods. The question is did those things really make tool failure less likely? Probably, maybe. I have watched a lot of destructive knife testing and hard use testing on Saks and tools. The softness on the SS found on Saks seems to prevent some of the catastrophic brittle failures of other blade steels. (Like when the Dutch Bushcraft Knives Channel on youtube tested the MKM Sak-a-like that has titanium scales and an M390 blade and it broke.) Where you can find some “hard use” type test videos of Saks that also baton and don’t fail that way. That said in my younger years I had a 1 layer Sak with a phillips backtool and I completely destroyed it when the pin and liners all bent. Stronger pin, liners, scales would have allowed me to keep torquing until the SS failed and rounded off. A lot of people have been swapping in Spyderco blades into their Mods, which come in different steels that you may prefer. In the mean time you could also just run the SAK as is and wait to see where it fails before making changes. If you poke around the “show me your sak mods” thread you will find some of those mods I mentioned.
Have you checked the ranger grip to see if it has stainless pins? I do remember taking some models apart that had those type in it. As far as would replacing the brass pins make it stronger? Yes of course it would. But it would need to be the right type to prevent gauling If you did decide to change to 1/8 pivots as suggested that’s a give and take. The 1/8 pivots will be stronger but you have to drill out the tools to make them fit thereby making the tool itself weaker.