You can polish the inside of the cyilnder with wire wool i suppose but it would take forever. The best tool for the job is a small bore hone. mine cost about a tenner.
The hone is fitted into a cordless drill and inserted into the cylinder, with plenty of machine oil to keep it lubbed up, it took me about 3 minutes to polish each cylinder, being really gentle to avoid damaging the bore any more.
the result is a nice shiny smooth bore, ready to accept clean pistons.
The next step is to inspect the pistons....