That’s OK, I’m in no rush. Your body number should be on a plate near your spec plate (that’s if you have a spec plate) on the passenger side (LHD) of the car. I believe the Alpine engine should have the same number stamped on it as found on the ID plate. Your number looks like it may not be the original engine, but that is OK mine isn’t either.
In regards to your alternator, you may have to do a little bit of work on the brackets, but not alot. I ended up using a Bosch alternator on my Alpine. You could also go to an auto electrician to find a decent second hand unit that still has parts available.