There are indeed many versions of this car, with different weights and powers. For example this turbo version of McLaren.
https://rmsothebys.com/en/auctions/mo19/monterey/lots/r0105-1978-bmw-320i-turbo-imsa/788201
https://delessencedansmesveines.com/2019/09/bmw-320i-turbo-gr-5-1978-e21-en-armure-de-guerre/
You have made your choices and they are consistent. The car is indeed very stable and easy to drive. As you know, in a driving simulation, your feeling depends on how you play? When you try to get closer to the real conditions (steering wheel, cockpit, screen and real size fov) too much stability can seem a bit artificial. In LFS (this is just my opinion) the super-road tires slip too much and the slick tires seem to me to stick too much to the track. The new tire physics will no doubt correct this and/or will make driving more subtle.
To give you another example, I drove a stock e21 in the late 80s/early 90s. From what I remember, I have the impression that if I'm still here to tell you about it, it's because it was more stuck to the road than yours
. With your Gr.5, it's the opposite. I feel like it's very stable. But, I have never driven this car in real life.
What I'm sure of is that your mods are great with LFS. Great job.