If your're looking for more performance out of your carbs, I can suggest that you get a larger air filter. I like the ITG, but for performance, you should have the biggest filter that you can fit. I'm going with a 6" Itg over 2" full radius velocity stacks, The larger filter needs a little (kindofalot) of coaxing to fit, but It'll feed your carbs MUCH better.
also, I've bought two sets of webers off of ebay and both times have had to do a very complete rebuild and rejet each time. Given that in most cases you get just about no knowledge of the carbs history, I'd reccomend a rebuild anyhow, a dirty carb can be very frusterating.
to sum it up, My 2c :
1) go for a bigger air filter and maybe stacks(make sure the filter leaves plenty of room around the stacks, & be sure to get full radius stacks)
2) be weary buying used carbs, be doubly weary buying them sight unseen.
Good luck, Its a great reward to hear a set of webers breath life into your alfa!