The best thing to do would be to:
1) Check
AniDB to see if any other or better versions exist.
2) Post in the New Torrents Requests subforum and mention the specific group or files you're looking for, as well as why you believe that version to be better.
For Kaikan Phrase, I couldn't even find any VHS raws that could pave the way to a soft-subbed re-release, which would at least be a marginal improvement. As people on the torrent said, there doesn't seem to be a retail DVD release anywhere. Apparently shoujo/josei/bishounen shows tend to lag behind on release formats, as they didn't start getting Blu-Rays until late 2010/2011.
But in most cases, BBT already has the best releases available. If the show is old/obscure enough that no newer/better versions exist, you'll have to either (A) deal with the low quality, perhaps by finding a smaller screen (1024x768 or 800x600 can make 240p tolerable) , or (B) find something else to watch.