I would put the stock seats back in. They are safer.
And I would have the IMS professionally done. A pro can easily do that job in a day.
At $80-$90 an hour indy Porsche shop rates it's well worth it from any shop that stands by its work.
If you make a mistake doing that particular job, oh boy. You write the check for the consequences. Not worth DIY savings in my book.
Even if you go with a higher cost bearing, if single row it will need to be replaced sooner than a dual row bearing, the intervals are shorter on the single row. So I would consider doing a direct oil feed (DOF) modification in addition to swapping the low-mileage IMS -- if it is indeed a single row bearing.
p.s.
Das Schield has a sale going on for hood and trunk dent protectors (they go on the inside), you get the the rear free if you buy the front protector. If you frequently lug items around in the trunks it's well spent money, especially on a lowered car.