Barb, you've been on the right track! In the Krook genealogy I found Elias Piispanen born 1826 Karstula. It's table 32.
That genealogy is very tangled, I'm descended at least twice from Simon.
Congratulations. You knew all along!
I don't have more info, but I refer to the Krook paper often. I switch back and forth from Finnish to English. It's not that my Finnish is good, it's because I think the name changes.
I know you've been working on this a long time, so have fun with all your Piispanens!!