Sorry- I've not been that deep on the 2.5, only the Roadster in an earlier life. This will get you down to the head bolts and other information you'll need for reassembly after the head. Be sure to send pictures when you do....
The Cylinder Head removal/installation process is pages 328 -334 in the manual. It appears that the head bolts are torx bolts.
Barrels and Piston removal/installation process is pages 340 -344.
Waiting on
@Neville Lush to come up with a piston/cam combo for the 2.5s for future plans