Well the thing with honing the plating is it might look like it'll work really nice, but you take away the cross hatch that all freshly plated cylinders need for proper lubrication. Also, even you manage to keep a good coating on it, it might start to peel around the port areas and cost you another rebuild. Honestly it sucks, I just ran into the same issue with my RM. But I'd rather spend the money on a replate and not worry about it. If you do try, and it works, please let me know. The muriatic acid trick only works to remove aluminum build up on the bore, like if parts of the piston heat seized to the cylinder walls.
But, I also ran into the same problem to see for sure whether or not it was plated. I heard of a magnet trick, if it was resleeved with a steel sleeve than a fridge magnet will stick to it nicely. My issue was the magnet slightly stuck, but not as strong as it stuck to the fridge. Conclusion: most likely plated.
