Just wanted to put this in the records.
The lower (larger) snap ring on the Barient 27 winch can be replaced with McMaster Carr part number: 91650A530
Its not the preferred stainless type (18-8) so I put a bit of grease on them before installing. Fit is perfect though.
I think this is mentioned elsewhere, but the top snap ring (as well as the pawls and springs) can be had using the Lewmar Barient Repair Kit: PK1 (West Marine part number 164582).
-dan