Nope. Buy the nicest manual and go from there...
Instrument cluster takes a minute to swap... literally. Ok you might have to move a couple of pins on the engine to body plugs to get it working.
Starting with an auto is harder as they have two ecus and bodging the wiring can cause chaos.
I must admit that I find it irksome when people say what their ideal Omega is and don't accept that they cannot simply buy them ready to go... suggests either a lack of imagination, vision or drive imho 
Looking at ebay.de, €6,000 would buy you a very nice, loaded 3.2... perhaps a better prospect given that clean original and unmolested cars are going to appreciate far sooner...
I understand what you are saying. But I'm not desperate yet. I haven't been looking for that long. Maybe after 6 months in I will start considering all the other more laborious ways.

I want the full leather interior of the MV6 and swapping a full interior will be hard, let alone finding one to swap in.
So the way I see it it's only a 3.0 MV6 for now.
A 3.2 will be a FL car and automatic. This means not only swapping gearbox but also swapping hood, bumpers, headlights, tail lights, rear quarters, well you know. I would have to keep it as a FL. I will only do that for a mint condition car, very low mileage and which ticks all boxes all for a great price.
I didn't realize the manual gearbox transplant was that complicated, since many people have recommended that here.