As you are no doubt aware, the SC14 is an old unit. It is getting harder to find a good one, and they are inefficient by comparison with newer Roots type blower designs. Twinscrew superchargers offer higher efficiency while retaining the driving characteristics of the Roots blower, but in the US in particular, centrifugal superchargers such as ProCharger are dominating the aftermarket for mechanical superchargers. In Europe Rotrex have done a lot of work in helping to develop centrifugal blower kits for BMW's.
If you can get (or already have) an SC14, would be happy with a modest increase in power and a decent improvement in low end torque, then by all means DIY the SC14. However, unless you get lucky and can find someone who can help you with the mounting bracket design, ducting and intercooler layout, you will be on your own. Engine management may also be a challenge unless you change to an aftermarket ECU or have a friend who is clever enough to be able to modify the factory DME to handle the changes in fueling and ignition timing.
The personal satisfaction to be gained from completing such a project is considerable, but do not underestimate the time and effort that will be involved. Do your homework before you pick up your tools and identify the parts of the conversion that you can handle yourselves and what parts may require help from experts. Good luck
Cheers...