I remember having the same questions. The search terms I recommend are "parts list", "head difference" "k24 blocks list", etc.
Of course it can be more convenient to just make a thread and ask, and that's ok, however I think for more general questions like these it will actually save you time, and you will learn more by temporarily focusing your efforts on your search terms. This has been my experience.
This site, as well as clubrsx.com and clubep3.com, are really excellent and have vast, vast amounts of information, including repeated, extremely detailed coverage of k20/k24 compatibility, differences, etc. So much so that you may automatically learn why you need certain parts (not only that you need them), thereby increasing the accuracy of your predictions and reducing or eliminating your dependence on others when confronted with problems and questions.
I truly have faith in your ability to find it. Good luck George!
Many, many parts are optional... In other words your question is difficult because it is inspecific. Remember, the k24 engine block is taller than the k20, therefore of course you will be needing a timing chain to match... The cam gears are the same diameter k24/k20 and the head's mating surface locations are the same, therefore you may use a k24 timing chain. I'm unwilling to give you more information for now.