One other thing to factor in to your calculations (well, in your head that is) - recording signal level.
Here's a quick visualisation:
You can see in there that the volume levels vary throughout the recording and that there is a considerable range compared to a lot of music that basically maxes out the signal at 0 dB (over 0 dB is where you get clipping). It's relatively quiet there in the middle of the second waveform, then the volume builds.
So while you can calculate what dB you theoretically want, you will only be getting that if the recording fits. Recordings with lower signal levels will still fall short.
The general trend in a lot of currently produced music (as has been for a while) is to max the signal out (as mentioned above), while in older recordings, e.g. Beatles, early AC/DC, etc., you have a lot more range.
tl;dr - You will be calculating a theoretical maximum and not the actual dB SPL level of the physical output.