Hi Gulliver and everyone,
One this page is some details of a fairly recent DIYish 68030 accelerator design for the a1000 / Phoenix Board by a German guy I think it was off a1k.org. Maybe there is some info for you?
http://www.gb97816.homepage.t-online.de/projekte.htmI wouldn't mind building the deinterlacer myself.
Good Luck!
John