It can be done, but I think the 7" screen will be too wide, maybe a 6.4 or 5.8 would fit better. With a earlier dash with the double din type opening their is enough room for a monitor (remove/replace ashtray and use the "pocket" for the screen and leave radio in factory spot. HVAC would not be effected.) You'll probably need a sheet of ABS or some matching vinyl to complete the job (maybe bondo the screen in place)
I would not do a flip down, it looks tacky, espcially infront or in place of your mirror. Good luck on the install, it will be sweet if done properly.
EDIT: There should be plenty of room in the pre98 dash even with the 7", remove the pockect, and cut out the plastic that use to be the ashtray. Put the screen in there, some shims and bondo (make sure you protect the screen) either sand smooth and paint to match the black texture, vinyl, or finish it with abs plastic.
