I can't disagree with anything that has been said, but I can reinterpret it. Or try to.
No argument that there aren't any vintage Marantz tables (other than the SLT 12, which would make restoring the 6300 look like child's play) that are really better than than their competitors. (And to say that they aren't up to the 7 and 9 is to state the obvious - neither are any other Marantz components of any sort (and precious few of anybody else's).)
But the context of the OP's question is that he wants something to work with his 70s/80s Marantz system. If you want to point out that the Marantz tables aren't the best out there, you probably ought to also note that the rest of his system isn't either. Marantz (or Superscope as it was by then) made very good equipment, but not necessarily (or, even, ever) better than other higher end mass market makers of the same time. I'd gladly admit that Marantz stuff looks great, sounds good, and that it, like most of the other Japanese equipment of the time, has been stunningly durable. But are Marantz receivers/integrateds/separates actually better than HK, Sansui, Kenwood, Pioneer, and so on? Maybe in some ways, yes, but in other ways, no. And are any of them better than top of the line separates of the time? I doubt that many would argue that.
I suspect that most of the Marantz tables of the time would match his system, and would sound quite nice. The Clearaudio rebadge is a fine, and probably better table, but it doesn't match his system, and it costs a fair penny. Other alternatives wouldn't match his system, and might also cost a fair penny.
I don't care at all about having a matching system, but clearly the OP does, or he wouldn't have one. And many people don't care about how equipment looks, but many do, and I can't help suspecting that the Marantz enthusiasts do respond to their very attractive looks. The fact that he is looking for a table and asking suggests that vinyl isn't his only, and most important, source. So maybe he should get something that will please him everytime he looks at it. That is a good start to a listening session.
This from someone who loves Peugeots. Every morning when I walked out of the house and saw my 505 wagon, I was delighted. All of its idiosyncrasies and repair issues paled in comparison to the exuberance of owning such a beautiful and fun car. Until it didn't.
But the OP, if he ever gets fed up`can always sell the table, and might even make money on it, since Marantz fans are legion.