My 2 cents.
KOF2K and some before it have been seen to use 64Mbit roms. (That is large and even TSOP roms this size are hard to find, amazing what the pirate did. The largest eprom's I've seen are only 16Mbit.) There are 8 42-pin C slots in the Cha board, and 1 32-pin M slot. There are 4 42-pin V slots, and 4 42-pin P slots.
I know that only 2 of the P slots are used in KOF2K1. Theoretically, if all the 42-pin slots are filled with 64Mbit roms, the maximum rom size would be 16x64 = 1024Mbit. If you include the M rom, which stores basic graphical icons and is usually 1Mbit, that makes it 1025Mbits. So there's plenty of space left on the current pcbs.
The reason why SNK broke the "MAX 330mega Pro-gear spec" was because of the advent of the 64Mbit rom. In future, using TSOP instead of DIP roms would further reduce space, hence more roms could be packed in, and perhaps even larger roms would appear. So the maximum size a game could be is quite irrelevant.
Anyway, back to KOF2K1, given that all the C and V slots are filled, plus 2 P slots, with 64 Mbit roms, and including the 1Mbit from the M rom, that makes 64x14 + 1 = 897Mbit.
And now my speculation, I reckon the P roms are 32Mbit or even 16Mbit each. Just a gut feeling.
I've seen a low-res scan of the prog board and cannot make out the size of the P roms which are eproms, someone with an MVS cart should be able to verify this. The eproms may be Toshiba's, AMD's or ST's and have a generic label, 27C16200 or 27C32200. Look for the 16 or 32, the rest just tells of array and type. The other roms are OTP roms which have no label about their size. Given the general ballpark romsize figure, they can be assumed to be 64Mbit each. (If KOF2K1 is larger than KOF2K)
So once someone tells us how big the P roms are, we've got a figure! (though, I think it's quite likely to be 897 or 833) I would have opened up my cart myself if I had one. Damn it!!!!! Have to concentrate on studies! Damn Tottenham Court Road Casino arcade not having KOF2K1... rant rant...
Another point to note, a 1024Mbit Neo Geo game is only 128Mbytes. A fifth of the size of a CD. 15 times smaller than a DVD. One wonders why the ports are so shit. Can't they just get the gravity in KOF right?!?!!??! Wouldn't be ranting so much if I could just play KOF2K1. huff.. huff..