Quality of content is sometimes more important than the quality of presentation itself. While the 2003 DVD audio is indeed compressed at 448kbps, it’s still the highest quality version of the original theatrical sound mix, with minimal tinkering, currently available. Take it from someone who’s studied the LaserDisc Dolby Digital soundtrack and DVD audio extensively over the years— repeatedly jumping from one mix to the other to compare and contrast. Aside from some noticeable tweaks in the dynamic range during the more intense sequences, they’re virtually the same mix, and absolutely the original one. Elements you can only make out in the centre and rear channels play out identically in both mixes.

If you want proof, the best I can recommend at the moment is for you to get ahold of the discrete LaserDisc Dolby track and 2003 DVD audio to hear the similarities for yourself and put all doubt to rest. Play them both in separate video player windows (my go-to has always been “K-Lite Codec Pack” version of Media Player Classic) and if you have ffdshow installed, isolate the centre channels in both player windows using the ffdshow audio decoder. Jump back and forth between both audio mixes, playing a few seconds at a time from the same scene(s), and see that they are, indeed, the same (original) mix. Do the same for the front channels, then the rears. You’ll find a lot of tells.

If your commitment to including lossless audio only is resolute, then go for the Dolby Surround version of the original audio— also on the LaserDisc. Other than that, the Blu-ray tracks are your best bet, but you won’t be getting the original sound design. So it’s either original but compressed (with exception to that aforementioned Dolby Surround mix), or lossless but remixed with questionable choices— a topic which goes far beyond the scope of this reply. Pick your poison.