Welcome Rat. There is a good write-up in the mods section on plating companies, but you'll need afew more posts to view it. So, in a nut shell, my personal preference is Power Seal located in PA. State of the art equipment and very good guys to deal with. Pricing is right around $185-$225 + shipping. (And you can supply a new piston or they will sell you one, but a New piston is needed!)
Only other 2 places that did as good of work for me in the past were Millennium Technologies and US Chrome.
Also, you will have to remove the cylinder head studs, powervalves, and the allen head bolt on the side before sending the cylinder out or they will tack on a service charge for removal.
Hope this helps, ROOST