The 201 is cross between Winnie 21 and Parker Bros., so one can't simply drop Repro barrels into 201 frame or vice versa even with extensive modifications. The only similarity to Parker Repro is position of outside pins and Parker replaceable plate on single locking underbolt.
The 201 isn't simply yoemans Repro of "Ole' Trojan", Mod. 21 or Mod. 23, but new design borrowing features from it's predecessors.