I replaced the OEM rotors on my '81 R65 6 years ago .
I now have EBC semi-floating steel rotors and EBC graphite pads .
Have I seen any noticeable improvement in braking, no .
The only improvement, is wet braking, which is greatly improved .
Which is a real benefit, seeing as I live in a desert !!!!!

So, what I am trying to say, is that you can put a lot of money and effort into this, but the end result won't be much of an improvement over what you have now .
The one thing I do recommend, is replacing the OEM rubber lines with braided stainless aftermarket lines and aftermarket brake pads .