Front Caliper Piston

Hello All.

I'm currently working on a 1981 KZ650 CSR bobber and I'm in the process of adding a front brake (b/c the PO removed the original). I bought the disk, caliper, and master cylinder. Everything is going great, except...the front caliper I bought on ebay is total crap. Its covered in gunk and all the seals are fried. So, I took the whole thing apart and plan on cleaning it with kerosene and I have a gasket replacement kit on the way. But, when I removed the piston I noticed a ring of slight pitting around the piston.

Since these are my brakes were talking about, I figure I'd buy a new one and not take any chances (that is unless slight pitting is not a huge problem?). But, before I do so...I figure I'd ask if anyone happens to have an extra one in good shape they'd be willing to sell me...or at least point me in the direction of where I could purchase a relatively cheap replacement piston. I hope this solicitation doesn't offend...I'm just trying to stop the bleeding - this darn caliper has already cost me much more than I was hoping to spend. Thanks for the help guys!