I'm a bit of a newb, but:
It looks like the company listed as "property of ____ocom" refers to "property of "Eurocom""
There are 3 carts it could be based on years of release.
1. it could be a very early prototype for 40winks.
2. it could be an early duke nukem zero hour
or 3. NBA Showtime: NBA on NBC
Its also possible that 4. it could be something else entirely. But I'm sure that you've already considered those ideas. an idea I had was also mortal kombat 4, but I can't find the release date of the n64 version, if it was different than arcades.
While I can understand that logic, there is the possibility that they didn't think it'd need 256MB at some point and used a 128MB cart.
Andrew, would you mind letting us know what it is when you find out? I'm rather curious.