More newPs, and a question!

These are the sellers photos, and some of you may have seen a few of them posted in a "help ID" thread. My question is, what would be the best thing to do to get the black crud off the penny, or would I be best off just leaving it? Looks like a nice AU to me, with a possibility of going unc...
1858 GB penny:

1872 GB Maundy 3d

1865 Finland 5 pennia (m. 480,000)

1864 Finland 50 pennia (mintage 104,000)

1873 Norway 12 Skilling (m. 490,000)

1871 Japan 5 sen

1870 Japan 10 sen
1858 GB penny:

1872 GB Maundy 3d

1865 Finland 5 pennia (m. 480,000)

1864 Finland 50 pennia (mintage 104,000)

1873 Norway 12 Skilling (m. 490,000)

1871 Japan 5 sen

1870 Japan 10 sen

MS66 taste on an MS63 budget.
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