Welp you did the LS3 swap after all
If it's still relatively healthy, you can simply upgrade it without having to think about a brand new, fresh unit of another engine
Stroker kit might be recommendable though, some of them can prolong the engine life since some are stronger than the stock engine internals (though in this case I'm sure LS internals are quite strong for daily usage)
Colour selection is a bit radical compared to other E92s around but hey, it's a good sign of creativity
Wheel selection is nice as well!
I think I'm quite confident over the direction your M3 is going
Mitsubshi Lancer Evolution III GSR 'Silver Queen' - Main Daily, Real Tuning/Street class TA car
Nissan Silvia S15 Spec-S (RB26 swap) - Second/Open/possibly Turbo class TA car (WIP)
Nissan Skyline GT Sedan HR34 - Spare Daily #1, grassroot drifter
Daewoo Tico (D16 VTEC swap planned)- Kanjo car (WIP)
Mercedes Sprinter - Parts and trailer van (mainly for S15)
Chevy Silverado CK1500 (LS7 swap) - Spare parts truck, hobby drag car, gift from Side to Side crew
Nissan 240SX MS13 Convertible 'Kaede' - Spare Daily #2, kyusha car
Toyota Mark II JZX110 'Meme Machine' - Missile drift car, currently broken, will be fixed
Ford Mustang Foxbody Hatchback 2.3 (Ford Modular 4.6 swap) - No purpose at the moment, FOR SALE OVER HERE! CLICK ME HARD!
Yes, I own too many cars, thanks for asking. All offers on cars for sale via PM unless announced later