[blykins]

That will work just fine as a spreader.

As for reusing old gears, just go ahead and reuse the original shims. However, with the new bearings, make sure you check everything including backlash and paint the gears to check the mesh. Also, set pinion preload for new bearings. I would use a solid pinion spacer instead of a crush sleeve, that way you could just set the pinion preload with the spacer shims instead of jacking around with a crush sleeve.