The M50 cooling system routing is the same as the S52. However the M50 uses a slightly different setup to do this and some of the ports are different diameters, adding complication to utilizing the stock hoses. In fact, as I recall every section except the main radiator hoses had a different size diameter on at least one side than any of my stock hoses provided. As a result, I got a little creative using existing used hoses from various models, working around pre-existing bends in the hoses to figure out a cooling hose routing that worked to mate the engine to the heater core inlet/outlet ports and to the expansion tank. S50 engines would likely find this task much easier. I highly recommend not cutting any hoses during removal as you never know what you may need
Unfortunately I do not have any pictures of the cooling system routing - I had to get very creative with using some hoses, a few of them were very tight fits (as in, very slightly too small diameter for the given coolant port). If you are doing this swap on your own, I recommend removing the M50 intake manifold before removing the engine from your car and noting the coolant hose routing. The M50 uses a big rubber hose to connect various coolant ports, the S52 replaces part of this rubber hose with a metal pipe and has shorter length coolant hoses coming off of it
When swapping an S52 into an E34, it is absolutely mandatory to use the E34 power steering pump. The E36 has a steering rack, whereas the E34 uses a steering box and they use different pumps. The power steering pump from the M50 will bolt directly on to the S52
Other than that, stock E34 radiator and radiator hoses work. For the A/C, just unbolt your stock E34 compressor and compressor bracket. It bolts on to the S52 as well