Certainly don't want you to go to the trouble of coming up with any race results or statistics to back up your claims. Heaven forfend...
But I'm still not clear as to which cars you are referring to? In reference to the lines I bolded above, you seem to be saying that S30-series Zs were raced in *stock specification* against modified Porsches? Where and when, please? I think it's nonsense.
Porsche simply out-homologated the likes of Nissan during the period that the S30-series Z was current. They created cars like the aforementioned models (911S, 911T/R, 911R, 911S/T, 911RS 2.7 Carrera, 911 RSR 2.8, 911 RS 3.0, 911 RSR 3.0 Carrera) which could be purchased from a showroom and either driven on the road and/or on the race track, with factory support in readily available data and homologated, race legal competition parts. Nissan were not even trying to compete with that. It simply was not on their radar. They took inspiration from the 911R for the 432R (two cars of which you'll find no more enthusiastic fan than me) but the 432R was an exercise in domestic race homologation for JAF sanctioned events and it was never intended for export. Nissan didn't bother with FIA homologation for the 432 or 432R, their most sporting showroom-stock models of S30-series Z.
I have been "following and examining the performance of various cars" from the late 1960s until now. In a previous post I mentioned that I was present at Le Mans as an 8-year old kid in June 1970 when Porsche took their first outright win at the event with the 917. I watched a Porsche 914/6 win the 2 litre GT class and a Porsche 911S win the 2.5 litre GT class in the same race. It made a big impression on me. I think I'm pretty well informed about the S30-series Z's race history (yes, including quite a lot of those pesky statistics) so I'm all ears if you can tell me something new. What have you got?