So I did some experimenting with Ryo today. Specifically, I trying to see if you could cancel from his zanretsuken into his NeoMax. My conclusion is no.
Just to review, the A version ends with a punch that sends his opponent flying back. The C version ends with a punch that sends them airborne. If you cancel into his NM from the A version, the opponent is already too far back for it to connect. Even in the corner, Ryo's fist just seemed to pass right through the opponent. It looks possible, but I don't think it is. If you cancel into his NM from the C version, the opponent is still too high in the air for it to connect. Disappointing. I was however able to connect a Haohshokoken rather easily.
In my opinion, the easiest way I've found to hit-confirm his NM (other than Max canceling into it from his ranbu) is:
EX Zanretuken -> NM
EX Hienshippukyaku -> NM
The advantage of these is that they can both be done anywhere on the screen, and they're not cancels, so you don't even need to be in HD mode to do them. If you ARE in HD mode, then you have enough time to follow either one up with more attacks without needing to waste any of your HD cancels. Those two EXs are really good.