Impressive!
Wonder what parts of what cars used.
Too bespoke and you'll have issues finding parts in the future.
Wonder what rear ratios are available?
My understanding is this is all out of a W201. A German ebay seller I bought some engine parts from also had apparently done this at his own shop, and it's a "done thing" in Germany. I'm not sure what they use, but it looks like the following were available for different models at different points: 2.65; 2.87; 3.08; 3.23; 3.27; 3.42; 3.46; 3.64; 3.67; 3.91; 3.92. It appears the 3.46 was most common across the various models/configurations.