The new Z will not be a Z35 after all. It will be a Z34 just like the 370Z.
Motor Trend spoke with a Nissan Executive if the Z would be a Z35 and they were told "no".
www.motortrend.com
Before the silk was pulled off of the 2023 Z, we asked a Nissan executive if the new twin-turbocharged sports coupe's chassis carries the Z35 chassis code. We were simply told "no." You read that right: by Nissan's own internal standards, the changes made to the latest Z are not significant enough to warrant a new chassis designation. The 2023 Z chassis is not internally known as the Z35, and it instead maintains the Z34 chassis code of the 370Z.
So that pretty much settles that. Yes, there will be significant changes to the new Z to make sure it is substantially different from the 370Z that came before it. The bodywork is obviously new, and so much of the interior has changed (and hopefully been improved) that the carryover chassis might not matter to the majority of consumers.
Motor Trend spoke with a Nissan Executive if the Z would be a Z35 and they were told "no".

Nissan Exec Confirms the New Z and 370Z Share the Same Chassis Code
This ain't no Z35, even if Nissan surely made huge improvements to the new Z's aging Z34 underpinnings.
Before the silk was pulled off of the 2023 Z, we asked a Nissan executive if the new twin-turbocharged sports coupe's chassis carries the Z35 chassis code. We were simply told "no." You read that right: by Nissan's own internal standards, the changes made to the latest Z are not significant enough to warrant a new chassis designation. The 2023 Z chassis is not internally known as the Z35, and it instead maintains the Z34 chassis code of the 370Z.
So that pretty much settles that. Yes, there will be significant changes to the new Z to make sure it is substantially different from the 370Z that came before it. The bodywork is obviously new, and so much of the interior has changed (and hopefully been improved) that the carryover chassis might not matter to the majority of consumers.