My 81 280zx has a N47 head on it, I thought this was a 280z head only. Were the pistons in the z dished? can i swap pistons to raise C/R or should I mill the head and, How much should I mill off? I live in northern CA, does anyone know of a machine shop that specializes in Z's

 

You engine has dished pistons. If you want you can swap in stock flattop pistons which will raise the compression to about 10:1.

 

That head went up to 80. If you mill the head remember that you have to shim the cam towers to keep the timeing chain tension correct. A machine shop will be able to tell you how much could be shaved but a good idea is to measure the combustion chamber volume and determine how much shaving will produce what compression ratio. Then before you have any work done make sure you can get a shim or combination of shims to compensate for the amount of material shaved from the head. If you're just milling the head then you don't need a shop that specializes in Z's. If you're having the head ported then it's probably a good idea to find a place that's done a few L heads