If its an aftermarket electronic unit like a Rosta should be fine, if its a vacuum servo you'll need a vacuum storage tank, mine did.
some one told my that webers where junk, cuz you can adjust them and the always run rich??? was he wright??
the only thing i heard bad about weber sidedrafts is, they need to be adjusted each day for best performance... btw did u mean a downdraft? or the sidedrafts? they are 2 totally differnet setups..