Hi I am a Nismo 370z 2016 plate car owner. Had the car for 3 years having been in a 350z DE for 4 years. I have had mine lowered on Tein S springs for context. Swift springs are a bigger drop and the ride will probably be too harsh. Personally I don't think the ride is harsh. For starters the 370z is more of a refined car to drive over the 350z. Not necessarily better, just different. I have driven the car for hours and not felt uncomfortable at all. Be aware the car is fitted with recaro racing seats which are sporty but comfortable. Of course only you will know given your health condition if the car is for you. Not sure where you are based by happy for you to come and have a drive if I am reachable. Good luck.
Finally, budget for a new exhaust as the stock exhaust lets the car down. I am not alone in this opinion. its shared.
Feel free to PM me with any questions.
Martin