Step up from Nakamichi 582 tape deck?


Have an option to acquire a very good working order 680zx.
At present have a 582 and was interested if those in the know would consider it to be a worthwhile upgrade?

Or would I need to go even further up the food chain? Zx-7 or 700zxl or?

I have just purchased a massive lot of tapes at pennies per tape so do not foresee me forsaking this medium anytime soon .. Lol.
uberwaltz
Yeah thanks, I had no idea on the tapes.  The Maxell UDXLII in particular still sound great and the case also seems way better than the TDK SA.  I bought probably 3x the Maxell so that's good news too.  I hate to play regular tapes because I believe they may coat the heads faster.  Anyway it's my theory and I am "sticking to it" pun clearly intended!
TDK tapes always ended up stretching the few time I tried them. Maxell UDXL-II and XL-IIS were my favourite by a landslide. TEAC cassette reel to reel tapes performed admirably also, but weren’t as readily available as the Maxell tapes. 
I’ve got a Sony TC-K570 3 head deck bought in the mid-90’s which I’m amazed with how good it sounds. Previously it was a Technics RS-M234X 2 head deck with dbx that performed flawlessly. I never got around to trying the Sony with my dbx 224 encoder/decoder but when I eventually do, I believe it’ll be utopian. 
Holy Moly!
You had to have dropped some serious coin for that!

Nearly the Holy Grail!