Just a wild idea I'm getting

I think there's an Aussie version of the M90 that has a top inlet for a carb. Might be harder to find, but these guys are developing a complete kit:

http://www.pentastarparts.com.au/sunshop/index.php?l=product_detail&p=2557

They have a rep for good customer service, so they might sell the parts individually. I'd try contacting them.