I can't help with the Barient info, just some general stuff. There used to be two systems of sizing: one where the number indicated the highest gear
ratio (e.g. a "46" meant a 46:1 ratio) and the other that indicated the maximum working load (in 100's of pounds IIRC). These days the ratio version dominates, but there are a lot of winches out there named for load, not ratio. There is only a rough correlation between ratio and load, so winches with the same ratio may have differences in SWL and winches with the same rated SWL may have differences in ratios. The only safe thing to do is find the original manufacturer's specs.
There is no standard for bolt patterns, so a change of winch often means new mounting holes. It is common practice to use a 6-bolt pattern (60 degrees apart), and in some cases the winch has a design that can only use 5 holes. However, if the winch has 6 holes then all should be used.
Good luck with the project