The pistons on the k24 from the crv do not have deep enough valve reliefs to accomodate the k202/a2 higher valve lift AND wacky cam timing,Youll want to clay the engine to find out for sure.
The k20a/a2 head will bolt on and will not require any modifications such as external oil lines etc..Just use the k24 headgasket...not too sure of the difference in head bolt length,but that should not be a huge problem.