If you get the shock towes, then you need the shocks too - or at least the shock shafts. Sway bars require the new arms, etc..
I.e. you can't pick and choose so much. You need ALL of the above, and probably a few other things as well.
Usually when this question is asked, people say "just get an 8.2 - the price for everything you need is so high it almost doesn't make sense."
What I did was (after selling my 8.2), get an RC8B roller with "Upgrade" shocktowers. This is a big part of the geometry. You could also get the +3mm chassis - but then you also need the longer rear center shaft... And so on.