http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=113180&prmenbr=361
There you will find a 5¬? Moroso wedge plate that sells for ~$35.
It's open design, but also very short, like 1/4.
I saw some other plates available on some marine websites for like $80 that had different angles.
"Carburetor wedge plate" seemed to net the most results when looking on Google.
Good luck.