An advantage of using an LCD is that you free up a lot of internal space, and also cut the heat back by quite a few degrees.

If you want to go with the internal display, you will have to keep the power boards, and route the power from the power supply to the board. The board would need to be a small form-factor and be mountable to the bottom (which is not hard). After going with the board, you will need to route the video cable that goes into the logic board and plug it into the VGA on the back.

Should work, thoughI think modyourmac could doublecheck since he could probably grab one at random and check to see if it works. I can't imagine it not working like that, and at the very most, you will just have to re-route the VGA cable.
MacBook 2GHz Intel Core 2 Duo w/ 2GB DDR2 RAM & 120GB SATA 5400RPM HDD
Canon Rebel XTI
Google Cr-48 Beta Laptop