The 6400 600 and 7400 Dura-Ace work well. Not light or lighter like the newer generations, but you're not going for that. Different comfort factor as well, since those old STIs still adhered to the ethos of vintage brake lever body design, now just with a shifting mechanism inside. It took until 7900/6700/5700 to get a longer lever body that more fully supported one's hands (if a handlebar setup wasn't conducive to it). If you can stomach the way Microshift shifters look, then go ahead. Otherwise, there's R2000 generation Claris which is 8-speed, but with the Dura-Ace 9000 (and newer) STI lever body design. It's even painted nearly the same grey as 6400. I'm updating an old Trek with an R2000 groupset, and aside from the fact that it is heavy (appropriate for its rank), is well finished with proven components, and it works with the "old" Shimano RD pull ratio of 1.7:1 (like everything SIS from 6-speed to 10-speed road-wise).

For silver stuff, going to the first generation of 10-speed (7800/6600/5600) is obviously a safe bet as far as the polished look goes. Shimano gave us some truly silver 105 in subsequent generations, even to 5800 (11-speed). I had a pair, but didn't have anything to build it with, so I sold it. [huge sigh] Too bad the modern Shimano "silver groupsets" are painted a limp variant of silver instead of anodized, which looks a billion times better. Literally no painted silver Ultegra or 105 groupset of the latter 10-speed and 11-speed eras looks good on any bike, new or old, IMO. Polished/anodized silver would be considerably better, and I would have likely had a groupset.