When to make a car a parts car?

that's wayyy high to be a parts car unless it's got a running johnny hot **** drive train that you yoink for another project and has a grip of tasty bits you can adios or roll onto your current heap.

one HUGE mitigating factor is model and rare/scarce/desirable. 318 2bbl nacho? likely parts. 340 S or big block, save to favorites.