I did the Weber conversion on my ea81 Hatch. The Hitachi worked ok, but it was paltry in the power dept.
Frankly, I got my Weber brand new in a kit off Ebay, but you can also just get the adapter plate and source up a weber 32/36 dgev from another car. They came on all sorts of vehicles, mostly 80's cars and trucks.
Bear in mind that when buying used, you might have to do a rebuild.
But yeah, Weber was a quick easy install, make sure you read the article is the USRM, that's what I used to install my weber, and it went perfectly. Oh, and get the universal throttle cable mount kit for that weber carb. It's a pain to rig up your own throttle cable mount.