I would likely spend about the same amount of time installing the engine and freshening the paint as parting. Has anyone felt they did better by parting than what they feel they could have done finishing?
I think you are grossly underestimating the time to do a good part out job or I'm not understanding how far you are thinking about going in installing a engine and freshening paint. IMO, a weekend to install an engine, and a weekend to buff the paint for four days total. By contrast, you can spend a week dismantling and other week cataloging and taking pictures, and a month cutting welds and popping panels to get all the saleable parts off that car. Some parts will go fast, others you will sit on for months.
Have I done better parting cars than selling whole, yes. But these also weren't E bodies either. I usually part the less popular stuff, pre '68 models or 4drs. More desireable models are almost usually worth more as a whole unless they are very complete and very, very rusty.