Ideally if I was just getting into the game, I would buy the cleanest shell I could find. Standard and Targa. (no tranny or engine... diff would be necessary, but have to be LSD (from turbo car).
That's how I would start if I was at day 1 with what I know now. From there it would be a 5 year build with a total interior tear down, subframe drops and rebuilds. Would build the engine from scratch with a good block/crank/head, find a rebuilt R154, plan on stand alone from day 1 and just go to town.
Probably run about 12-15k in parts by the time I was done (that may be a little low), but I would have a proper car bumper to bumper. I find the biggest hill I had to climb was the body. The second biggest was the drivetrain, but it had the most options and paths open. Wanted 2j (single tubo), but ended up with a built 7M purely by accident and happy to be stuck there.
All depends on what your dream is with the car. The more time you have, the better. You can't beat a good shell though.. very hard to find up North where I live...