My teenage daughter's 73 Charger's 318 engine seems to be on its last leg.
What are the small block re-engine choices if the two most important factors in making this decision are:

* must be able to be bolted into the car's existing carburetor, k frame, motor mounts, automatic transmission, existing power steering pump, alternator and Bouchillon bracket for Sanden A/C compressor (what I call a "plug-and-play" swap out); and

* get the most cost-effective solution?

If we stick with a 318, what is the range of years for a plug-and-play swap out?

If I want to go with another displacement, what years and what displacement small blocks would be plug-and-play for my situation?

She likes the car because it had decent mileage, always starts and runs easily, is comfortable and smooth. Power is not a huge concern for me, but a bit more wouldn't be a problem because it has a 2.76 rear end.

Anything to avoid? Anything particularly attractive?

Thanks, Moparts.