08 IRS to S swap?

So my brother bought an 08 525 IRS and we have had nothing but issues with the boots since he got it. It wants to act like it is losing power than stalling every time we get it started and a shop by our house said it had to do with the ECM so any insight on that would be nice!
However, my main question is I found a 525 S frame and shaft for cheap and was wondering if I could swap the engine off the IRS and if the front suspension was the same or if they were totally different setups. Once again any insight is better than no insight ?
Thanks!