Which Nakamichi to choose?

Great info, @cleeds . And the term archive is a misnomer. My plan was to make high quality copies of albums that can be listened to without the time and effort of playing vinyl.
  I agree that R-R is an amazing format even today, but requires money, time, and a relationship with a good tech for use in a home system. I enjoy the setup and recording process. Then comes the satisfaction of sitting back and listening to some outstanding music.   
   For me, there's no other format that sounds so pure and organic.

I use Nak 682ZX on a weekly basis and send it to Willy Hermann for service every five years. It also has custom transformer and $1500 interconnects to pass the signal to the amp.
No, it does not sound as good as Nottingham Spacedeck turntable. And I use only the best tape there is - Maxell Metal Vertex. But it does sound very very good. I used to use Dolby B from time to time but no longer - more disadvantages than advantages.
I suggest paying more and getting 680ZX, 682ZX or ZX-7. My preference would be 682ZX, but it is rare and more expensive.
I started another thread regarding tape some time ago. For me nothing sounds quite like tape. My Studer reel-to-reel project is on hold but I'll get there in time.

inna,

Thanks for mentioning Willy Hermann. Just enough info to link me to what I have been thinking about for years. Thanks again.

I think, he now does only overhauls if it is the first time that he works on your deck. His 'overhaul' is not at all ES Labs overhaul who literally completely disassemble and reassemble decks and claim to make them like new or better. But they charge thousands, so I told them to go to hell. Willy does what needs to be done and tests everything in the process. I paid something like $650 the first time and about $350 second and third times. The wait time is a few months, at least it was last year.

inna

... His 'overhaul' is not at all ES Labs overhaul who literally completely disassemble and reassemble decks and claim to make them like new or better. But they charge thousands, so I told them to go to hell.

Really? You tell people to go to hell if you don't like their price? I'd say ES Labs is fortunate to not have you as a customer.