Full conversion Non M E60 to E60 M5

[vaynardx]

Hi guys, sorry if my search effort in this forum is not thorough enough resulting multiple threads.
but Ive got a question for those who had experience in the swap.
Car to begin with is 523i and the reason for swapping is due to the tax in asia region that make a used 05 m5 priced at $125k US.
1. Is the engine and SMG gearbox bolt straight up to the Non M e60?(engine mounting area, transmission tunnel, etc)
2. is all the driveline (running gear) bolt straight up too?(front & rear axle, complete suspension).
3 which areas of the swap is the most difficult?
Best Regards.