if you don't want to drop the engine down from the bay (which will take more effort, but give you more room to work), essentially it needs to be stripped down as such:
View attachment 20431
View attachment 20432
springs can be changed without removing the head by pumping compressed air into the cylinder to keep the valves from dropping.
then "just" reinstall everything back - implies making sure timing is properly dialed in, etc etc. also some gaskets should be replaced to avoid leaks - at least high pressure pump, valve cover, and vacuum pump.
One important thing, if not dropping the engine, be very careful when refitting back components (especially in tight areas, such as when refitting the timing covers, as they're relatively brittle if not handled properly). take your time to put things back together correctly, and follow the fricken service manuals on how to do it properly. don't rush things or you'll be in a world of trouble.