Depending on the damage to the cylinder, I would just have it repaired. Repairing is a lot cheaper than buying used cylinders and the coatings these days are apparently way better than the original nikasil. My top cylinder was totally stuffed. Nikasil was a mess and had a number of cracks in the ports. I had them repaired and all is well (apart from my son dropping the bike and damaging the fairings).

Andy

Bandit7