Hi Roxxxsmom,
To me personally, "dialogue-heavy" is qualitative in the sense of what is the non-dialogue stuff that happens. If this "other half" is made up of nuances of body language and people looking out of windows and rain gurgling in the gutter, than this other half is merely atmospherics enveloping the dialogues. The dialogues are the core, the spine, the motor driving the book forward.
If, on the other hand, the core, spine, motor is the action; the plot is driven by chases and shootouts and twists and doublecrosses and things going boom, then it's the dialogues that are atmospherics enveloping the action--it's an "plot-driven" book, even if dialogues take up 70% of the page's space.
On the quantitative front, I'd first use the word search program to locate the "saids" and their alternatives, then do manual job on the untagged dialogues.
Further, there are the character thoughts, the inner dialogues, the narrator-provided back-stories--these combine into a third stool-leg that balances the whole deal (the fourth being physical descriptions of people, houses, mountains, etc.). If these thoughts and narrations are all or mostly catering to the action plot--it's X, if these are mostly atmospherics around the actionless interaction between the characters--it's Y.