I was actually planning to do something with this game a while back but I never got the time to do so. In fact, I could probably add to this endeavor a bit if I had the time, but all I have to show at this current time are these dated (2003, ZMVs for ZSNES 1.36) vids.
Pack 1
Pack 2
Original Site - Scroll to Killer Instinct.
There are a couple more things I learned over the years with some of these characters, since these really aren't that impressive, but it'll give an idea of what I would've done like...3 years ago. The big thing I had to go on was the GameFAQs guide provided there and people that constantly frequent zbattle.net. You'll learn quite a bit getting your arse beat by them.
I think the longest Ultimate and Ultra is included in these, however. There are a few characters in the game that aren't included for highest ultra. I think I got Spinal's 5-hit-juggle in there as well. Fulgore shows off a few missed variants of combos in pack 1; you can do that on an Ultra but you'll only get 31 hits instead of the max 32.
A thing to remember about breakers as well is that if you connect a combo when a person has 0 health (whether in the yellow or red health) they cannot combo break. That would be the time to show off ultras and killers and be free from combo break worry. Additionally, if this is REALLY for speed, going for low-hit combos are the way to go. That was one thing I hated about this game: the higher and higher the hits the less and less damage it gives for each new hit. I think the max tops off at about 50% damage for any given combo, no matter how long it is. A way to get high damage at the start, though, is attack with HP and HK attacks.
A way to go about the with Orchid for unbreakables, let's say, is her Ichi (DB-DF+MP), HK, Ichi, HK, Ichi, HK and then finish with Lasaken (D-F+WP). That's 7 and is completely unbreakable and is rather quick too if done right. That's one example and there are plenty more in there.
One thing I couldn't master was finding a way to make unnamed combos that dizzed the opponents continually. I got constantly beat by this tactic when I went against pros in zbattle.net. They would do certain combos that would dizzy after a significant (far more than 2, like normal dizzies) hits and it would not call it a combo but rather a dizzy. Anyone who knows that tactic and knows how to use it will have an easy time setting up additional combos, since the CPU would be helpless to block at least the first hit.
The only problem I can really think about with making a run for this game is that the computer, literally, cheats. There are certain combos that the CPU can create which are otherwise impossible normally. There are times where the CPU will 'spaz out' into a combo and go into a dizzied coma afterwards for a second and they're different per each character. I'm not sure about how to recreate it, but it has happened several times with me playing on standard level 4 and continually owning the CPUs. That's just one instance. There are other times where the CPU can find ways of combo breaking OUTSIDE combos as well. I've had times where I've completed a combo and knocked them down and back and all of a sudden the CPU says that they get a combo breaker and I get knocked down.
That would be the top two things that I can think of that you would have to win against. It might make for a nice glitch addition to the run but it also might be a pain in the ass to go against. The game itself is hard enough.