If i was to make my own vindicaire assassin i would make him between 109pts and 111pts. Independent of course but never able to join squads, infiltrate would be good, and fearless. A 4 up inv save from fast reflexs too!
his wargear (if i was to make him) would consist of a mask of some descripion that 'spys' that reduces cover saves by -1 and sees 2D6x5 in dark conditions.
A suit that is 'stealthy' would make him hard to see, and so like shooting at him at night, in the dark. If it was already dark then they would only be able to see him at half the nigh see distance.
His gun would obviously be good, a sniper gun with an AP2. He could also have some special ammo 3, would be good but only able to use each once. A breaker of shields that would ignore inv wargear saves, a peratrator 'turbo' that casue 2 wounds and rolls 3D6 for AP. and a firly hell shot, that wounds on 2+.
He also would ahve a pistol like a bolt pistol but with a +1 strengh and AP2.
Oh an some ability to pice out any model you wish in a squad. His profile should be the same as in the rulebook.
This is only my persoanl oppion though...you would have to buy the real codex for the REAL rules of course.