Cubase CAN do this, and I think you'll find the old Cubase VST (that you have for Win95, or whatever) will do this. For certain, VST5 has it, and I've been on Cubase since the Atari days. I am 'fairly' sure the older versions had this command.

Changing length by a percentage is not the way to do this, each pedal on/off is most likely to be different. If your current sequencer can't do this, is there a piano-roll screen that can show you notes AND the CC64 commands at the same time? If so, you grab ALL the notes that are sounding when the CC64=127, and then drag their endpoints to the point where the CC64=0 is. Again, Cubase has a modifier to the pencil tool that will make all selected notes stop at the pencil point. Drag that to the CC64=0 and on to the next.

I am sorry I can't confirm any other sequencer (I've been a Cubase addict since it first came out), but I would be surprised if most modern ones DIDN'T have the command. Although bargain sequencers like PowerTracks are OK up to a certain point, there comes a time when you want to do more sophisticated editing, and Cubase is what you REALLY need.

As you are on an older computer, VST5 should be perfect for you (and is, IMO, better at MIDI than later versions!). Want to average the levels of all the snare backbeats, while leaving the rest of the snare notes alone? Cubase can do this. Want to convert all CC7 (volume) commands into CC11 (expression), and scale them to be less extreme? Cubase can do this. Want to take all Cowbell hits LESS than vel=64, even them out and bring them up WITHOUT touching the higher velocities? You get the picture...

Editing styles is about as demanding on a sequencer as anything I've done. Don't hobble yourself by trying to do it on a bargain sequencer...