I'm seeking opinions on upgrading this Nishiki Medalist. The bike originally came with Suntour Cyclone II derailers, downtube shifters mounted on one braze-on in the center of the downtube, and Superbe brakes and brake levers. The brake levers are non-aero.
I have a Superbe rear derailer (currently mounted on the bike), Superbe aero levers and Suntour bar end shifters. Although these are not original, they are period correct as this model was offered in 1984 and 1985. The Medalist is a fairly rare Nishiki and would be ranked higher than the International. To the best of my knowledge it was never catalogued. I'm 50/50 on adding the bar end shifters, but I like the rear derailer and I like the idea of adding aero brake levers, especially since they are Suntour Superbe.

So should I remain a purist and leave it all original or make the changes? Thoughts appreciated.

I would leave the shifting alone. Those top mounted self triming shifters were very cool. The part to adapt them is pretty obscure and will require hours of surveying bike shop parts bins and the ebay. There are ways to make it other shifters work but you would have to use some sort of clamp on the DT either for the shifters or the housing stops.

As for the areo levers I think that would be a nice upgrade.