I have a 5800X3D and 4080 with a G2 and I find it very balanced in MSFS VR, being sometimes slightly CPU limited and mostly GPU limited.
While I get very good performance for my settings and render resolution (160 OXR and DLSS Quality), I am not able to run everything at ultra without dropping performance below what I find acceptable. Nonetheless, I have everything set to a level where I am unable to discern a noticeable enough difference going to ultra, so it is not of great concern to me. If you really want ultra everything, then a 4090 is what you want.
Re CPU, as @BearsAreCool510 says, I’d go the 7800X3D over the 7900X3D, unless you really need those extra non-3D cores for productivity tasks.