Setting up a M104 and 722.6 to run as a swap

[Mighty190]

My 450SLC needs a new engine some time in the near future and I came across a 3.6 AMG M104. So I now have that engine and a spare subframe I acquired from a parts car. I'm starting to collect parts so I can hopefully build this powertain on my second subframe allowing me to do a rebuild, mate everything, and figure out mounts and the pan. Then do a winter switcharoo next year. Leaving the exhaust, trans cross member, driveshaft, and a large portion of the wiring to be done with the engine in the car.

If I want to run a M104 with a 722.6 580 transmission and retain the electronic shift can I pull the bellhousing from a w140/w210/w202 M104/722.6 W5A330 car? Then use a later 722.6 with the W5A580 rating? Will I need the earlier conductor plate? If I wanted to save some time and cost up front can I stick a W140 M104/722.6 ecu in the car without carrying over too much of the peripheral electronics? I'm guessing there is a version around 1995-97 that uses the 5 speed and old key that is not paired to the ecu. Would this combination use a W124/W202 style 3 pickup flex plate? I would not mind getting the swap physically in the car and going back and doing a megasquirt in a year or two.