That dash peice will be a easy start..buttons screen and facia
Is all well worth the price as it takes a lot of time to fab somthing up half as nice..
Problems i can see are....
Screen quality could be woefull..might not be but chances are if you want to drive it from windows or android the screen res will be a huge step backwards from a nexus 7.
In my experience flashing of a chinese tablet/sterio/phone or anything is next to impossible unless you can do some serious rom building.
Next is 8" screens are not known for there brightness.most are quite low.
Some of the newer windows tablets have decent ones.these could be a option to swap into the new facia.
Mabee fit a dell venue pro 8" in the space and use the facias button board with a joycon.fit a slot loading dvd drive if needed and load your favourite frontend.
Nexus 7..odroid with the supplied screen
Options are limitless!! But most require some work.