recommendation for a high end analog system

FWIW, Dover is correct; the Triplanar does fit fine. I now recall that I had my Triplanar mounted on my Star Sapphire once upon a time. The only issue is in the vertical direction wrt the max extension of the VTA adjustment and the height of the platter or rather the sunken depth of the arm board. Anyway you’ve made your choice.

My recommendation was to go for the Eclipse system as biggest bang for the buck.

I see that there is a Triplanar II upgraded to VI on audiogon. TP VI is supposed to have effective mass of only around 11 gm. With my Denon 103R retipped with Sapphire cantilever, I probably need a higher mass. I can increase the effective mass with a head shell weight. Where does one get such a thing (other than taping pennies)?

Yes, 11g is the standard quoted effective mass for the 9-inch Triplanar, regardless of the "version" as indicated by Roman numerals.  And yes, that is probably not the best choice in terms of effective mass for the Denon 103R, but it is probably a good choice for any of several other modern LOMC cartridges that have higher compliance.  You could add any 5g weight at or near the headshell of the TP and be in good range for the 103R.  Double-sided carpet tape would do the job as adhesive. Thought you had decided on a Graham.

No, haven’t decided on the tonearm yet. Is there a more professional way of increasing the tonearm/head shell weight than using a tape?

I meant get a 5g weight and use the double-sided tape to affix it to the headshell.  You can use any sort of flat disc that weighs 3-7g.  You would need an accurate scale to weigh the chosen object.  Or ask Tri Mai, the maker of the Triplanar.  Maybe he has a more "professional" attachment for increasing effective mass of the Triplanar. I think a US nickel (5 cents) weighs 5g. If not a nickel then some other common US coin does weigh 5g. There are innumerable options for adding weight.  You can also wrap the arm wand in tape, which also reduces resonance. Etc. Don't forget also that the weight of the cartridge itself adds to effective mass, and the Denon is fairly hefty.  Aftermarket mods to the Denon often also increase its weight (see Zu and a few others); you could look into one of those.  (But I personally would not spend more money on the Denon.) Also, use heavy screws (and nuts if needed) to mount the Denon; that also adds to effective mass.