Regarding wrestlers 40d vs present, there's a huge detail to note: wrestling does far less now than it used to. In 40d, wrestling = grappling, dodging, punching, etc and as was pointed out by Grendus the EXP growth rate was ridiculous. Now, wrestling = only grappling. There's a separate skill for dodging and another one for punching.
2 further factors go into separating 40d from the present: the new materials/physiology system and the new attribute system. Back in 40d, your wrestlers were quickly Legendary +5 and probably were ZOMG statted in all 3 attributes too because everything (including socialising) trained up strength/agility/toughness with no upper limit (well, there was but most creatures were almost 2 orders of magnitude below it). In DF2010, dwarves have an upper limit to how far they can train their attributes (once attribute training is debugged) and the new materials system (yet to be fully balanced) heavily punishes you if your attacking material is inferior to the defending material.
So then, what would we need to bring back the mythical martial artist dwarves of the past?
1) Attribute training debugged - possibly also modded to raise the limit.
2) Metal fist weapons or revamped gauntlets - something that lets you use a metal's properties instead of your bare fist flesh properties when you punch. Not sure whether you'd want the metal to be as dense as possible or as hard as possible given DF physics.
3) STRIKING (and dodging) skill training - what you're interested in is killing them, preferably by punching them 50 tiles into a wall.