If the sound of a highly tuned MB/AMG v12 as used in the Zonda R (search YouTube) does not give you goose bumps and raise your blood pressure then a V8 of your preference is definitly the wiser choice.
If it is the sound of the exhaust of these exotic cars you are aiming for, just remember, Ferrari, Lamborghini, and others spend a considerable sum of cash getting the exhaust note just right. Dropping in a V12 and putting in a homebuilt exhaust with aftermarket mufflers may end up disappointing you.
I too like to see interesting engines used, Garry's rotary engine is an outstanding example, but for the majority of us, spending 20 grand and up on an engine, then 10's of thousands and months of labor to get it to run, the complete lack of support, along with outrageously high parts prices on these specialty powerplants is just too high a cost to bear. In Europe, I can understand the want of a BMW/Mercedes powerplant, they are the Ford and Chevrolet of Europe, easier to get parts for than a chevy/ford crate engine.
I cant wait to see Nils completed car, it will definitely generate more interest in using that engine.