Well you got my opinion.
Here is a link to the OE staggered setup had it been an MSport.
http://www.bmwstylewheels.com/bmw/351
It shows the proper sizes and offsets.
This isn't written in stone as some want lower offset which pushes the tire outward.
Higher of course is more inward, it is all a matter of taste.
Also just to state the fact, reps are cheap for a reason.