Ah, thanks for the clarification. I doubt it would work. You'd be better off saving your coins until they started providing Wii U games on club nintendo, if ever they do.
The only evidence to support is that the wii shop codes are numeric, e.g.
1234 5678 1234 5678
and eShop codes, at least those for 3DS, are alphanumeric, e.g.
A123 BCD4 E56F G789H
And it would be kind of dumb for them to use the same code for the same game on the eShop. And there's no word of N64 support, so you might be waiting a while.
At the worst, if you buy now you're getting a $10 off coupon for the N64 game for WiiU. Damn this is confusing.