I did that and it's all just an indecipherable mess. I do see lots of matches. I guess I'll just be safe and hang on to it.
Googling has helped very little, as I'm seeing answers, dating back to ~2015, ranging from "of course you can" to "OMG...whatever you do, DON'T!!!".
So...
It sure seems like I could, you're right, because they've all been migrated to Photos and appear as iPhoto events. And I saw a lot of the same folders when I "showed package contents" with both libraries (iPhoto and Photos).