Don't take it personally. If you're missing the hood insulation center piece, the Alfa snakebite headliner is similar. It was present when the car was on Bat last year - https://bringatrailer.com/listing/1990-ferrari-testarossa-40/ The starter positive shield is NLA but you can probably find a used one: https://www.ricambiamerica.com/126505-protection.html
V12 Ferraris are very special and iconic and reflect the true Ferrari spirit. It is clear that the 512 tr is a classic and special Ferrari model and among the options, it seems to be the most suitable car to keep in the garage. However, since I don't have much information, I can't make a clear comment. Between the 550 and 599 GTB, I can say that they are both very good cars. I have owned a 599 (with F1 transmission and low km) for about 4 years and just sold and I know many aspects of the car well. In fact, although they are fundamentally similar, we are talking about two very different cars in terms of usage. While the 550 Maranello is a much more comfortable and enjoyable road car, the 599 is a GT car produced with much more racing instincts. In addition, the 550 is now quite old, and if you cannot find a well-maintained car with a clean history, frequent but not serious malfunctions may bother you if you intend to use the car regularly. As I said, the 599 is a harder and sports car, therefore it is more suitable for sporty driving and of course it is more reliable than the 550. Considering all this, I would recommend going for a clean and well maintained 599 GTB.