Duplicating aged shellac

I am repairing a very old (~150 yrs) grandfather clock. The poor thing spent much of its life near various fireplaces and as a result has a finish (shellac) that has taken on the texture and appearance of old leather. It is really quite beautiful.

We want to retain the original character (and finish) to the greatest extent possible, even though I am having to replace a considerable amount of wood just to make it structurally sound.

I can match the color well enough, but the question is: how to duplicate the aged texture? I've tried test pieces with varying thicknesses of shellac and applications of heat, so far with no success -- I can create a damaged finish, but not the "grain" that looks leather-like.

The patina and texture is so attractive that I am loathe to simply amalgamate the finish and produce a nice smooth finish. My plan is (was) to spot the repairs to mathch color and texture, clean the existing finish, then apply a light overcoat of sprayed shellac to preserve and protect.