I'm not sure if there are any differences in terms of spring rate etc, but as far as size goes, they should both fit. They both have the protruding reservior on the top don't they? The battery box will need cutting to accomodate this.
Is it really taylored to weight, probably not... whether you'll find it an improvement, I don't doubt that you will
Oh, and 20wt oil is probably a bit harsh.