Tranny and flywheel should bolt up; they're the same engine. I'd recommend getting new clutch parts, i.e. clutch disc/pressure plate/throw-out bearing/master cylinder/slave cylinder.

Not sure about the center console or brake booster and brake fluid resevoir, but I'd recommend getting them anyway if you have the money...that way you won't have to go searching for them if you do need them.

Ask for the drive shaft/tail shaft; get new flex discs. You'll need the reverse light switch, neutral safety switch, possibly the speedo cable and AC and cruise control relays.

I don't think the rear end ratio is much different, but don't take my word for it. All I'm aware of is that the '87 and older autos had a numerically higher ratio than later models.

Where are you located? Do you know the owner of the wrecker? I've been trying to track down a whole 5-speed 190e 2.6, but I may end up having to use a 2.3 instead and just getting the flywheel from a wrecker.