Need help with differences between LS1 & LS2 fitment
As far as reluctor wheel, that depends on your year. I did not have to change mine, or have to go to a box(lingenfelter sells a box to convert from 24 to 58tooth wheel) so, what you can do is get your year, around an 05 LS2, and you may not need anything but to plug it in and go.
I think I had to notch my passenger side motor mount bracket, not the actual mount. Not sure if I am forgetting something but that is what I have done a couple of times while putting LS2's in LS1 cars.
LS3 heads WILL fit an LS2 but you will then need a square port LS3 intake manifold to go with the LS3 heads.
Engine harness, is the same for the most part.

