Without hashing up an old thread - I've been running a 3.2 on a bone stock 98 GTP for about 5 years now (50k miles on the pulley). No issues and the most KR I could get was something like 4* at WOT using 85 octane.
It's all over the map with these motors (or really any).
The best answer here was "you never know unless you scan". That is the truth.
See if you can borrow a scanner and see if you have any knock now. If not, I'd give it a whirl without any mods.