Three problems - - - - -
"Welded", not seamless
"Annealed"- - - - -"soft"
"Stainless"- - - - -no idea if it can be heat treated to the proper hardness.
Few poeple I know of, except maybe a particularly obnoxious machinist, have the right type of heat treat facilities to harden a fabricated shaft properly to work with needle bearings running on them.
Other than that- - - - -good idea!
Jerry
Let’s pretend a guy could source something similar of suitable hardness. Would it work then? How hard would it need to be to prevent wear with the needle bearings and a good oil supply? Im learning here.