I believe HP has it labeled as cut off, I think it's supposed to cut spark and fuel at set rpm. In the speedometer section there is also a MPH setting. You can't real take that section out of the computer, unless you are good enough at hex coding to make your own operating system, but the max value you can set is 256mph, and either 10 or 12k rpm. It has been a long time thought that the vortec black box had a hard coded rpm limit of 6k that can't be over come, but that has recently been proved false, you have to set the dwell settings for the rpm you wish to reach, otherwise the coil doesn't charge properly and it is like a rev limiter.IIRC, my 1998 ECU has engine RPM and vehicle speed limiters with hysteresis, i.e., an upper "cutoff" threshold and a lower "re-enable" threshold, for each. These are tunable.
I might assume all 96+ are similar.
I presume the ECU cuts fuel / stops firing the injectors.
Having the ECU retard the spark would be an interesting approach. Blowing both airbags and/or engaging the ABS would be as well, and maybe turning on the hazard flashers too.
All the ve tables and spark tables only go to 6k, so what ever you have set for 6k is what it will do past that.
As far as I know HP and EFI live are the only ones that you can custom tune a vortec black box with. No a lot of demand for anyone to hack them, as anyone who wants to tune one, either invests in one of those two platforms or swaps in an ls pcm, 0411.
Universal Patcher has a vortec table search folder in it, but I don't think anyone is interested in developing it with all the attention on ls pcms these days.