Hmm... I thought the whole point about alignments such as chaotic good was having questionable methods.
I guess it'll hinge on how petty his need for revenge was and is.
Tbh, I'm not sure revenge against killer the babyeater of the earnibbling people can be that petty. I guess you mean proving people like the flaming fist wrong, though?
I mean, he is willing to torture an innocent man to get, what he wants - not exactly good aligned.
I think, Wyll desperately wants to be good, but has some very dark streaks in his character.