I've had three 325ix's and a Touring is my dream car.

My current one is a 1988 coupe with a five speed, previously I had another 1988 five speed coupe and a 1989 automatic coupe. The automatic car was pretty doggy. As for the potential swap to a five speed I'm pretty sure the transfer case was different than for an automatic, so make sure the parts provided with the car allow for that. Also, the differential gear ratios were different (on US cars at least, a five speed had 3.91 gears and an automatic was 4.10. Since this is a euro car that may not apply.)
This car looks pretty clean but they like to rust behind the lower body cladding where it may not show until it's pretty advanced. Check carefully along the rocker panels and the lower edge of the front fender for rust bubbles. It looks like the window weatherstrip on the driver's door may be getting kind of crunchy. Obviously all the touring specific parts are going to be difficult to replace, especially in the US so check the tailgate closely including around the seams for any rust issues. Some of the front end suspension and drivetrain parts are getting hard to find (and are expensive) or are NLA, so watch for wear and noises when test driving the car.
Something to watch for is the splines on the transfer case where it connects to the front driveshaft can strip out, because from the factory the driveshaft doesn't plug far enough into the transfer case. The common fix is to shim the driveshaft where it bolts to the front differential with some washers, so the splined end is pushed further into the transfer case. I had it happen to one of my cars; I was able to get the transfer case rebuilt at a place called
https://www.zumbrotadrivetrain.com in Zumbrota, MN - they're a large facility that usually deals with four wheel drive trucks but they were able to take care of me too.
An important information source is the iX registry, at
https://www.325ix.com/ixregistry/iX/ I don't know how active it is anymore but they have extensive FAQ and repair info sections online - I recommend reading them. The newsletters are also on the website and are worth looking through for tips and tricks.
Edit: I forgot to say that since it's a euro spec car, of course you need to make sure the importation and title paperwork is all in order.