Funny that it seems like there are quite a few people on here who are constantly recommending mark at MG classics. I've seen his stuff on ebay, always buy-it-now, for insane prices. Just recently I called him for a shift fork shaft. Right off the bat, he was pretty rude to me, and it took me quite some time to get him to listen to me long enough to get it through to him what I needed. Just wouldn't shut up for a second. When I finally got through to him, he wanted $85 for it. MG cycle said I could have a brand new one for about ten bucks more. Fuck off and keep your parts, jerk!
I see ambo/eldo manifolds on ebay all the time, and they don't seem to fetch a real high price. That said, I'd just chop off the welded-on carbs, spend some time with a die grinder and a file and use what you've got.
I'll also add, that there is a guy that is always selling Guzzi and BMW parts on ebay from Austin TX who goes by Lamontsanford. I've gotten a number of things from him, and he's been a pleasure to deal with.
I wouldn't bring her home to Mama, but Mama ain't home tonight.