You will be happy in a few years if you do NOT clean your chips today. I used to do the same thing, find the best solvent, the best brush, and the right amount of elbow grease. I am sorry now when I look at the old chips I did clean.

Leave them alone and enjoy the history. If the chip is so filthy you wouldn't enjoy it, don't buy it!

I did the same thing with rare coins back in the 70's when I collected them. Cleaned coins are very undesirable today, and I find I reduced the value of a lot of my early US coins by 90% by "making them look better".