I've done all my interiors- you can see my 'J' at henryjpage.homestead.com/DragonJGaryBonds.html -first off is the car painted and mechanicals done? Interior should be the LAST thing. Then see if the seats fit what you want or find donors from another car you like. You can recover seats, but it is a big job. Door panels can be handmade with masonite and fiberglass or RodDoors has plastic panels you can cut to size and recover. The sky is the limit, so just look at other's interiors and get ideas, then plan.I made my own overhead console out of steel to install overhead stereo and my armrests are flame designs in fiberglass. Don't forget seatbelts!! Have fun with it but make it the last thing on the car you do. Good Luck!