I don't think this is going to work. Aside from the fact that it will be technically very difficult to manufacture natural sounding new lines for Vader and that Luke's current lines don't work with this storyline:

1) the ESB scene is shot and played as a hugely dramatic revelation. Vader revealing that Obi-Wan tried to kill him after he turned to evil would not engender the type of reaction that Luke has in that scene;
2) the premise of the idea is to "redeem Obi Wan and make him honorable again" but it still turns upon the fact that "Obi Wan didn't mention this. He lied!"

There's not a lot of redemptive/honor-oriented difference between Ben concealing Vader's relationship to Luke and concealing his attempted killing of Vader.

Anyway, in ANH, Ben isn't lying to Luke to manipulate him, he is trying to protect him.

Not to mention that the ESB scene is one of the high points of the OT as it is - and if it aint broke...