Following up with this thread:

The new lens arrived today from an eBay seller in Japan, it looks great and I'm quite excited to use it.



The front element has some scratches, this was mentioned in the sale, but the glass is in otherwise beautiful shape.
The scratches shouldn't show up at all, or maybe they'll help with the diffusion!

What drew me to this lens was that it met two criteria I had: it's of the right vintage (60s/70s) and it's single-coated. It was also affordable, which was important, but less so than the other two points.
What clinched it was the Copal 3 shutter with 10 blades, and not the usual 7 blades. I'm hoping this will be a factor in any work I do with this lens, especially portraits.



Thanks for everyone's help, very much appreciated.