Polishing the Swing arm will be alot of upkeep. I have 2 custom snowmobiles that the Alum tunnels are polished. I had the initial polishing done by Metal Masters in SLC UT. Then for upkeep I use Mothers Alum Polish. Road grime, water stains ect will quickly take the shine. Its constant upkeep. Thats why I have an V-nose Enclosed Trailer.
I just rebuilt my CR500 and was going to polish the swingarm as well. I think it would look great, then I thought of the extra work to keep it that way and decided not to do it. I understand that you can have clear coat put on polished alum and it will protect the shine. However it dulls it a bit. I think there is also a polished Alum powder coat color that will have that same type of affect, but I have not seen any of that. Maybe someone else on here has.