1973 rallye 340?

[mike340magnum]

i have a 1973 charger rallye 340 numbers matching car, it has a regular roof, not vinyl roof, 727 slap stick. what is it worth and how does it become defined as a coupe? also what are some good things to upgrade the 340 magnum in this car? it currently has massive domed pistons in it and the thermoquad still on top, a car buff friends determined the pistions to be like 12.5 : 1. will this work well with the bigger 360 heads to bump up compresion ?

[ODZKing]

To answer one of your questions; a coupe is usually a 2 door with the rear windows stationary.