Throwing the idea around again of upgrading the 066 to a 880. This could be a hopeful dream at best. One thought I had was setting the saw up for 3/8" chain instead of .404.
It's tough to measure kerf precisely, but generally, a smaller kerf is a good thing for milling.
I would not even consider .404, though we have a few members who are happy with .404.
Aggiewoodbutcher did quite a bit of chain testing on 120cc saws, and settled on .325" chain for up to 42" bars, 3/8" on longer bars. He used a 9 pin sprocket with the .325".
Only problem with .325" is that milling bars and chain are not easy to come by.