I'm running the 2 piece gaskets with my twin carbs and haven't had issues yet, not to say I wont in the future though. While you have the manifolds off, get the single piece.
Definitely take a look at the thickness of each of the ears on your manifold. If it's a lynx item, you can garauntee that they will vary significantly, they'll probably even have some taper on them.
It's not hard to fix, just get a file onto them, not on the Head side of the manifold obviously. Your exhaust manifold should be quite accurate.
If you get extractors you'll likely find they have a thinner flange and you'll need more filing.