OK, first thing you do is cover up that chevy orange engine with some real Pontiac blue
From there, if it runs and drives, are you planning on driving it while working on it. The body work could be completed a little at a time while you still enjoy the use of the car. Unless you are really super motivated, ripping a car apart to do work and making it undriveable in the process causes a loss of interest if the project takes to long. I'd start on the body, do the interior next, upgrade any brakes etc that need attention, then do whatever engine work you're thinking about.