jason you will need to replace the butterfly plate. maybe this one would work i dont know check and see
MERCEDES BENZ THROTTLE BODY - USED - eBay (item 190441195768 end time Jan-05-11 03:18:15 PST)

you can also contact maxbore and send your unit to them to be bored out to 78 mm. they will then make a new butterfly for the new diameter bore. cost 125$ plus shipping.
lastly maybe rudy has a spare t/b plate he would be willing to part with. shot in the dark.
anyway you go your ride prolly shouldnt be driven until the plate is replaced