Good day Alex, You did not mention it in your comment, but have you tried the usual used parts sources like EuroSpares, GT Car Parts, Rutlands, FerrParts, etc.? These would be your first place to look. Cheers, Sam
My brother is not going to forget anytime soon when his clutch and flywheel were lost in the post office... 9 years ago this was already hard to find and close to 1000€ if memory serves me well. Not sure it is any better now. Some members have shared their address-book a while ago, I do not know if you came across this thread (https://www.ferrarichat.com/forum/threads/who-do-you-purchase-from-for-your-400.590400/#post-146351460), but you could give all these suppliers a try.
I believe I have the parts you need. If you are still looking, please send me a personal message and I will come back to you with details and photos. Regards WM
Maybe Fidanza https://fidanza.com/aluminum-flywheels/ They have a custom flywheel department. Olivier