I've got a GSM-1 on its way to me, so I can't tell you (yet) how mine looks. I found this of a completed SG kit, though it's slightly different from the GSM-1 as it has a maple, not mahogany neck. https://www.buildyourownguitar.com.a...l=1#post171893

There is never any guarantee with these entry level kits about how well the body timbers match. Some will be fine for stained/dyed finishes and clearcoat, whilst others are best used with solid colour finishes. It's always best to see the kit before deciding on exactly what sort of finish would be best. However, the two-piece bodies are generally selected with far more care, so should be pretty well matched for looks. Plus the plantation grown mahogany is normally pretty consistent in look and colour as well.

I've never had an SG, though I've got a few LPs, so the different control arrangement isn't that annoying to me. However, it's one of the things that stop Gibson from going legal on the kits, as they certainly couldn't be classed as accurate copies. PBG used to sell LP style kits, but stopped selling those for fear of possible legal action. You could probably plug and re-drill the control holes in a more conventional way, and then use a mahogany veneer on the top to cover the plugs up, but that would still leave a small veneer edge line around the edge. Or else you do it and go with a solid colour.