Yes, if you're not using lavc then there are no lavcopts.
That said, I'm not advocating preserving ancient MPEG2 encodings. MPEG2 dates back to the late 1990's and is pretty much only used on traditional DVDs and by some terrestrial HD broadcasters. MPEG4 is considerably more efficient, as your size comparison indicates, and I doubt you could see the difference in video quality on-screen.
These days the codec of choice is H.264, a variant of MPEG4, which achieves even better compression at equivalent quality. Most streaming sites like YouTube are encoded with H.264 as are most unauthorized video rips out there on the Internet. The drawback of using H.264 is its higher computational demands for decoding. Older hardware with slower CPUs generally can't decode HD H.264 encodes in real time. Modern video cards often include hardware H.264 decoders these days, in particular NVIDIA cards which offer the VDPAU interface. You'll see postings here from time to time complaining that they can't play modern video files on their computers. Usually they're trying to play a 720p or 1080p H.264 encode on computers whose CPUs aren't up to the task.
I suggest you watch a few minutes of the two files you mentioned above and see if you can detect any obvious quality differences. If not, then I'd stick to MPEG4 or use H.264. Handbrake is a GUI-based DVD ripper and video converter that makes creating H.264 encodes pretty painless. It also handles things like multiple audio and subtitle tracks with ease.