Replacement of 535C with 582

Good day all,
I operate an ASH25EB glider equipped with a Rotax 535C.  I do not currently have (touch wood) any issues with the motor or drive system - but I am cognizant of the fact that the 535C has been discontinued and finding parts is close to impossible.  

My question to the experts.  When the time comes, and the 535C loses reliability, what are the considerations/mods I need to perform to fit a 582 into the 535C's place?  Mounting positions?  Overall dimensions?  Gearbox and ratio's?  Gearbox flange position?  Exhaust compatibility etc...

Thanks

Jean du Plessis