Unfortunately, (if I did my research right), the eShop for Nintendo's current consoles is region-locked, and games (or versions of games) from other regions cannot be bought on your Wii U.
It appears that it is possible to transfer game data using SD cards, so possibly if you bought an SD card from overseas that contained a NA version of Donkey Kong 64, your console might play it. However, I cannot confirm this method as I have never tried it myself so your console might recognize the game is from another region and then block you from playing it.
There are also many articles and videos on the internet on how to download the Wii Homebrew channel onto the Wii U, like a good one I found here. When doing so, though, from what different links I read/watched it always seems that you will need one of a few certain Wii games to do this (here is a list of all the Wii games possible to do this with).
So if you successfully install the Wii Homebrew Channel onto your Wii U and then learn to use the Homebrew Channel, you might be able to download the North American version of Donkey Kong 64 on that.
Good luck, I hope you're able to do it! :)