39 tooth would be the small/inner ring for a Shimano 6500 double, or really any standard double. Is the current 39t ring actually ramped/pinned? The 39 off a double wouldn't be, it might have a couple cut teeth at best.

9spd Dura-ace had some odd gear combos on the triple, quick googling says it was 53/39/30. So you might be looking for a Dura-ace 9spd middle ring, not sure if anybody else made one.

Edit: Well there you go, that link has a 39t middle. Also this is the Dura-ace ring set, but It looks pretty beat up: https://www.ebay.com/itm/Shimano-Dur...e602:rk:4:pf:0