Do you know for sure that they're brand new and never been plated? If so, you can clean them up with a bit of fuel soaked rag and use them with the correct piston - assuming you can / have got them.

If you aren't 100% sure you have brand new barrels then make sure you carefully check the piston and ring clearances. Or they won't stay new for very long...

In fact, new or old, be sure to check the tolerances and if it's all good, then go ahead and use them.
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