I had a long talk with a friend yesterday who has about 12 Saab 900's as parts cars and he knows a lot about the front suspension and the drive shafts, and I know where I will be buying my front suspension. He also has a lot of ideas about the rear suspension - I may be able to use a Honda / Acura multi-link suspension. Which would be great for passive "steering" that improves the handling. I'll be visiting his shop (up in New Hampshire) fairly soon to get a first hand look at all the parts.
The front track of a Saab 900 is listed as 55.9" and the front track of CarBEN is ~51.5" so roughly 4 1/2" narrower. And the width of the
BRUSA SSM1-6.17.12 motor is 250mm (9.85") with the
6.4:1 reduction and differential which is 235mm (9.25") is probably much wider than the final drive of the Saab 900, so the length of the drive shafts will have to be shortened.
If the tall and narrow Bridgestone tires become available, then that might change the equation of the width somewhat.
Also, does anyone have experience with transferring a VIN from a old car to a newly built one?