Thanks! I fully agree on the exhaust - looks even better in person.
Unfortunately though - it doesn't fit

That was a really nasty surprise that left us quite confused. I think I got the root-cause of how it happened. As I was refreshing this thread and collecting and reviewing the pics I did notice that on the pics from the exhaust fabricator the used engine bushes are the taller e34 ones while I am using the e30 M20 ones. Pictures also confirmed that I didn't sent him the bushes with the mounts and most likely miscommunicated what bush is used since I have set of both e30 and e34 bushes around and have forgotten what I did use due to the long periods between updates. So there you have it proven - if you prolong you put yourself through more trouble...
While I was contemplating on how it happened Yordan went on and got that rubbing runner chopped and reshaped:
And had the engine back in to confirm fitment:
Very very happy to see this - he finished it just yesterday evening and I only have the pics for now. What follows is still tedious though - engine out again, exhaust manifold removal, welding, shielding it in heat tape, assembly with yet another new gasket and then hopefully the engine can go back in for good.
So that is exactly where the project is at this point in time. I will do my best to put the updates as they come for my own best - this is indeed a good way to keep record and not forget things.