whats the right offset degree?
 

I have an 1981 sc i am having steel widebody fenders put on and having the whole 89 930 setup put on,i have been shopping around for wheels and have been hearing i need offsets on my wheels or else im going to have to use spacers,my fuchs are going to have spacers on them until i buy a set but i hear there very dangerous for everyday use ,performance products have 7.5 X 17 (Positive 23 Offset) and 9 X 17 (Positive 15 Offset) for turbo twist style 1 wheels,i really dont want to spend the money just to find out that they will stick out to far,thanks for youre help