There is a letter about this topic somewhere in the library or forum. I found it a couple of months ago and have now lost it..
It says that Hartley suggested 65% for rigid singles and 70 something percent for swinging arm.
If anyone finds it, please let me know.

Best to do these things while you can still remember what day it is..
Every retirement day is a new adventure..

I'd use the 28mm. Agreed re the compression.
Even a 7.5:1 piston would be a big improvement.
I think you'll notice improved power throughout the rev range and a small loss of 'genteel' character.

I've always worked on the 'if you can't see them they're not there' principle - and so far it has worked brilliantly.

Bored Vincent?

I think standard gearing is a bit low for current roads, particularly if you are doing any highway riding.

Sounds like a good plan John. I have a less obvious but similar issue with some powder coating that dad had done on the '37NG. The 'gloss' bits that aren't satin have orange peel and pin holes. I figure the powder coat is a good base and I'm reluctant to have even more metal sandblasted away. A frus...

John, I'd like to post something constructive - but I'm having too much fun at your expense.
What do you plan to do?

Beautiful bike.

Awesome! Thanks.