It is sorry, but it works. The HRB confuses me, but it also works.
Yes the Gator blade will work, but why change from the dual cut to a gator.
I don't give a crap what people say about the Honda especially for mulching.
Nothing works better than a Honda for mulching. Two blades are better than 1.

We mow Bermuda grass down here ,the mulch plug catches more grass than it mulches.
Perhaps someome has a similiar model and has a "fix" for the plug.