Most of the parts companies that I know about with parts that fit are replacement parts specifically for Macs. You need parts that work with the motherboard you buy but fit inside the MacBook body. Depending on the MacBook model you start from, you will have to figure out the battery that fits that model, some were removable, and meets the power requirements of the motherboard/hard drive combination you use. Can you match the external access port locations with the leads from the motherboard and does it use the same types of ports, FireWire, USB, etc.
Getting back to the display/graphics module question, you have to have a graphics module with exactly the same display leed connections to match what the display wants to see.
There are so many questions to ask yourself, it may be better to also look at available PC laptop cases to see if that would be a better matchup.
All of this should be doable, in theory, but you need to start a list of everything that has to match up since you are talking about starting with a case manufactured for specific parts, and you want to use different parts.