Linking works now but I don't know how it will behave when Jim archives the old forums. Not sure how the "html-mummy" works together with linking to specific topics/threads
I was wondering this as well, so I just gave it a test run. I have copied my "Gearing Class Odyssey" thread across from MSW to the new site and dropped a link to the old archived thread into the first post on the new site. It appears as boxed title in the new thread (circled in YELLOW in the image below) and when clicked opens in a new window on my browser.
I will be restarting some of my longer threads this way on the new forums, not copying the whole thread across.
Hope this helps.