Congratulations on finding one of these gems. Only a little over 300 '88's made it to the US with the five speed. Mine has over 200K miles now and is getting a little rough around the edges, but it's still a fabulous, reliable and great fun to drive car.
I can't offer too much advice about the SRS system except that it is EXPENSIVE to fix. If you're lucky, the most common problem is the contacts inside the steering wheel.
I know the 205/60's will be okay, but I'm not sure about the 215 55's.