The distortion sounds like an FOV issue. If you can’t find a way to adjust the FOV, choose 1280×960 or 1280×1024 as game resolution and zoom out a few notches (image zoom in the vorpX ingame menu or [SHIFT][MOUSEWHEEL]).
In many games this an easy way to quickly deal with FOV issues since vorpX 0.9 (if you can live with the image not filling the whole screen).