Without an analog joystick, you are going to be severely limited in the games you can play. I can not think of one game that didn't use the analog stick off the top of my head.
The good news is that you get lots of games that will work. Including Rave Race which alone makes it worth doing! The only thing you can do is think about what games you want and then see what the controller config was like on the N64. Don't laugh but I am busting out a 9 button CP granted the N64 only needs 8 buttons.
(1) (2) (3)
(8)
(4) (5) (6)
(7) (9)
1-6 represent the traditional 6 buttons layout
4-7 are Neo Geo
For N64, I will not be using 1 even though I will map it to L
2,5=A,B
7=Z
4=R
3,6,8,9 = c-pad (notice how they almost form a diamond shape like on the N64 :)
Now, people have warned me against doing this but I figure hte button costs $2 each. So $4 per player. I'd rather try and fail rather than never try at all. Mappings are not definite yet but they are my starting point. I think the above is good for Wave Race, but not something like Street Fighter.
Enjoy the discussion:
http://forum.arcadecontrols.com/index.php?topic=104864.0