Definately go the 8" !!!
You wont be dissapointed... start with an Aerpro double DIN adapter / faceplate (Aerpro have SEPERATE BRACKETS which is important).
Junk the brackets, cut the sides to the right size (i mean the opening where the screen will sit) with the dremel, and fibreglass the shape of the bezel.
I used a piece of perspex which I waxed and marked the viewable area of the screen on as a template for making the bezel section.
The back (which neets to be flat for the screen to sit against) went something like this:
* rough sand (36 grit) the entire back of the fascia
* build up a 10mm high 'bead' of auto body filler on the flat sections
* let it GEL (dont let it dry hard)
* use a razorblade to trim the messy 10mm bead into a thin strip of filler which sits 10mm high and about 3mm in from the very edges of the fascia. It should be around 3 mill in width all around. it doesnt need to be perfect.
* let this dry fairly hard.
* with a sheet of 80 grit on a piece of glass / tile / something hard and flat, sand the back of the bezel GENTLY until its even all around.
You will now have a curved front (aerpro fascia) to match the dash contour, and a flat back to sit the screen against.
Now the front - making it into a screen bezel!
You would have trimmed the lower section of the aerpro to make the screen sit in the middle.
* Cut a piece of perspex larger that the size of the screen.
* Mark out the screen's viewable area in the perspex ON BOTH SIDES with a permanent marker.
* masking tape over the permanent marker lines on one sode to protect
* place the side that hasnt got tape up against the fascia as if it were the screen.
* WAX THE PLASTIC!
* tape into place
* mix fibreglass resin / hardener
* brush on some resin in teh obvious places - we want to fill the gaps and create a smooth down slope to the line on the piece of perspex. this will take some patience and maybe a few attempts
* place strips of chopped mat (cloth is too hard to mould for small things like this) and brush with resin etc.
* try not to be too sloppy and go over the lines - just makes it harder later.
* if the fibreglass start to gel - STOP and move on to the next steps. whatever you missed you'll have to finish in teh next hit.
* wait until the resin gels. we dont want it hard - basically the consistency of, say, a rubber band. it will still be sticky to the touch but not brittle in any way.
* cut, shape, shave, etc with the razor blade the rough shape / angles of the bezel.
* remember to use the likes you drew as a guide. If youve glassed over them and cant see, turn it over and peel the tape off - thats what the lines on both sides were for - the tape on the back was so the line wouldnt rub off / get covered in crap!
You should aim to get the final outline of the screen perfect (razor blade and clean cut while the resin is gelled). You can fix this with more resin if its off a little.
The angled parts / smoothness etc should be of main concern right now - get the right shape and good lines around the screen and you're laughing.
Finally let the whole thing dry for a few hours, turn it over, and fill all the gaps in the back (remember to leave room (3mm) around the perimeter of oringinal aerpro plastic to sit up against the dash.)
Finish with auto body filler, get it nice and smooth, prime and paint as normal. Some of the other threads on the forums here should be able to help you here.
I initially finished mine in GM black, but i'll be refinishing in a 2K black with a matting agent to make it look more original.
To mount the screen - I took the LCD apart, left all the boards connected except for the buttons and IR receiver (using hacked webcam / USB for reverse cam so dont need to switch AV / VGA etc), masked off the viewable area of the screen, and urethaned the whole lot to the back of the dash, including the hacked aerpro, which was first araldited in to the exact spot.
I secured the boards with urethane also, stacking them one by one as the cables allowed, seperated with a thick piece of cardboard and a dab of urethane.
Let it dry for 3 days before you consider putting it in the car again - it bloody stinks like hell.
Let me know if you need further info.. in terms of pics i dont really have any of the build (generally dont use a camera when ur working with fibreglass) but have a few of some of the stages of the build and some of the finished product. I can take the dash part off and take some snaps of the back of the whole lot next time i do a full clean of the car (i go spaz and pull seats out etc lol). Im sure these will help / motivate you somehow.
Please feel free to ask any other q's - happy to help if i can.