Exhausts for vega

As some of you may have seen I Have an exhaust on my Cometa made by Mick Abbey (also have one in the for sale section) Mick has indicated that he might be able to reproduce a exhaust to work with a standard 75cc machine. He needs some info before he could start such a project. I.e port timings, and width, compression ratio ignition timing etc. Does anyone have these or where I might find them. Or a original condition barrel he could get measurements from?

I think ive got a barrel, jem will know all of the port timings.