Darth Revan and Darth Malak vs. Exar Kun and Ulic Qel-Droma.
Round 1: Fight occurs in the fields of Dantooine.
Round 2: Fight occurs in the SF but only Revan and Malak gain the amp.
Round 3: Fight is still on SF but both sides can draw on said amp.
__________________ "Vader's pulse and breathing were machine-regulated, so they could not quicken; but something in his chest became more electric around his meetings with the Emperor; he could not say how. A feeling of fullness, of power, of dark and demon mastery -- of secret lusts, unrestrained passion, wild submission -- all these things were in Vader's heart as he neared his Emperor. These things and more."
__________________ "Happiness is a lie. Life is horror. The light is always dying all across the universe. The last star will flicker out someday, when it does, all that remains is shadow. And I will be its king!"'-Amahl Farouk
It's not the cleanest measurement of two combatants, but the d20 SW guidebooks have Kun and KOTOR Revan as very very close in ability, with Kun inching out on DPS thanks to his saber. Even in terms of Force knowledge and ability they were close.
SOR Revan is an entirely different animal, and I think he would make Kun work for it. Malak, on the other hand, needed Star Forge amplification to be a contender, and while he's not a weakling, Ulic is a legendary lightsaber duelist, and I think in the end he would win.