Stick with bismuth shot, or Tungsten Matrix if you can find some. TSS is harder than steel and could damage the choke area of the barrel. NICE shot is another alternative, if you can find some. Stay with lighter shot loads in all of these to help protect the old wood from excessive recoil.
Some of the latest bismuth loads have been getting some bad press of late. People trying to use it in some really tight Full and XFull chokes in vintage doubles have experienced shot fragmentation when passing through the choke. I have several hundred of the BOSS bismuth loads, which have gotten some of the bad press, and mine kill ducks way better than steel, but I'm not using them through chokes much tighter than .025". My bismuth reloads that are loaded with the old Bismuth brand pellets seem to do fine through the tighter chokes, .030" through .043".
Might be worth your time to read over this:
https://www.randywakeman.com/How_Nice_is_Nice_Shot.htm Ed didn't mean to imply "beware" of RST. He actually said "be Aware" of it. That's my guess anyway. With Ed you never quite know for certain.
Good luck. Anxious to see the pics.
