When to make a car a parts car?

Someone please tell me.

I'm still on the fence about my 72 400 4 barrel Charger SE with factory SG.
Solid unibody except one side of the cowl. No engine.
Needs both quarters, a roof, a durchman, the cowl work, and one fender.
Cool factory bronze color.

1 of 503 made with 400-4 and SG 3.23.

I paid $1200 about 10 years ago because I valued the axle at $500, the bucket seats at $500, the hideaway headlights at $500, the clock/150 rallye cluster at $250, and doors and good fender at $100 each.

I agree 5K is too much for a rusty, six cyl car that doesn't run.