I don't remember doing the primary gears, myself. Since my setup was so primitive compared to yours, the couple of trannys I did were a whole winter's worth. After that, I showed it to others, who wore out their own arms, all on CB750K engines. One of them was the guy who came up with the 2x4 loading routine to speed things up, but he was one of those that Hollywood could photograph as a "classic biker", with biceps that could remove my living room wall easily, too. (Yeah, we called him "Tiny"...)
If you decide, before I get my 2nd tranny ready, to offer it as a service, PM me. Please...? I really don't think the old bearings will make any appreciable difference, as it is the face steps on the gears that need the mating-clearancing routine. The alignment of these teeth, in real running, is not real tight. You can see that once you get it all cleaned up: Honda's backlash spec for new gears is around .005", which lets the larger ones rock nearly .030" at the teeth. The dogs do the torque coupling work, the gear teeth do the rotational transfer work. So, tiny improvements in meshing smoothness pay off big in rotational transfer efficiencies. That's one of the reasons better oils improve the HP thru these boxes: less face-to-face losses because the oil is slippery-er...