I doubt you can outreach 2handers with a 1hander.
Weapon lengths themselves aren't really comparable between weapon types. Animations add or reduce from the effective length of an attack. So in effect if you for example compare a thrust of a 120 length polearm (Bec de Corbin) and a 120 length twohander (Great Sword) they will NOT effectively reach the same lengths. Due to the way polearm is held polearm is from 15 to 61 units shorter depending on animation. This animation effect on reach is very noticeable especially with one handed weapon stabs. Even a short one handed sword can outrange a twohander or a polearm with a thrust in some cases. It's worth a note that polearms in general have longer options than twohanders to compensate for the shorter reaching animations.
1h
Overhead = +0
Left-to-right = +0
Right-to-left = +19
Thrust = +61
2h
Overhead = +15
Left-to-right = +17
Right-to-left = +13
Thrust = +80 (This may be slightly wrong with the new stab animation)
2h Polearms
Overhead = -15
Left-to-right = -7
Right-to-left = -2
Thrust = +19
1h Polearms
Thrust = +50
(Source: http://forum.c-rpg.net/index.php/topic,9245.0.html)
2H swing get between 13 and 17 reachbonus.
conclusion: 1H thrust outreaches 2H swing unless the lenght difference is bigger than 44.
the 2H thrust for shure will allways outreach any 1H.