Hello Rick. I agree with hatman. If you're after a "working" rifle only, go with the least expensive blued version. That way you will not feel so bad if it gets a few dings.
One thing about the Navy Arms version that is not just cosmetic is the factory short stroke. By the way, that is a great price on a Navy Arms!!
If you intend to use your gun, whatever version, for CAS competition you should also plan on an action job. The guns are quite useable out of the box, but not really race ready. Also, the factory guns tend to eject brass way out to the front which results in lots of lost brass. That can be corrected by modifying the shape of the top of the carrier or by new aluminum carriers from Pioneer Gun Works as part of their short stroke kits.
I expect you will be happy with whichever version of the Miroku '73 you choose. But, I tell you, that Navy Arms version is sure something to look at!!!!
TR