If you want to do Yorktown then Enterprise would be an easier conversion.
Ed is right about the Tamiya 1:700 kits, but if that's your scale, that's what you've got.
There's plenty of research material on the Yorktown class ships, so the Tamiya kit can be modified to represent CV 5. The island is too skinny, but that can be fixed, if you want to work at it.
One of my planned builds is to convert the Tamiya Hornet CV 8 to a late war CV 6. My plan is to kit bash the Hornet and the Mini Hobby Enterprise, to take the Hornet Island, hull and flight deck, and use the MH cat walks, etc. which will get me reasonably close. Then some tweaking and photo etch will make up detail changes. I've considered then using those left over mixed kit parts and doing a Yorktown in Dry Dock at Pearl before Midway. I know the MH kit will have some trouble, but it is all doable. My research stuff is good.