You're right on both counts, and I'll correct the README.
On the GX point: I overstated it. GXSetDispCopyYScale only takes values >= 1.0,
which is where I got "cannot downscale vertically" from — but the interlaced
copy modes do achieve 2:1...
vc64_240p
Patches an N64 Virtual Console channel so it outputs 240p instead of 480i, running on Nintendo's own emulator. Optionally also removes the emulator's dark filter.
You keep everything the official emulator gives you — the per-game...