I've had several seemingly unaltered S&W revolvers measure differently at different places on the cylinder. I'm reasonably sure this happened at the factory. And these were guns from the desirable "classic" post WW2 to 1970's era.

To me, it's a "school of thought" issue rather than an actual mechanical/functional issue. My understanding is that all of the clearances you gave are within S&W specs. So my school of thought is, shoot the gun - if there are no other issues and you like the way it shoots, leave it. No need to fix something that isn't actually broken.

I can understand people wanting their nice gun to have the proper fit, but if the weapon functions as you like and is safe, please realize that a local gunsmith could potentially change the shooting characteristics of the gun in his attempt to get the cylinder gap right. Just my opinion. Best wishes.