Just a follow-update . . .
Installed the razberry package with no issues.
API key carried over without having to re-enter.
Did have to force interview which worked for 2 powered devices, but failed with a battery PIR (Monoprice)
Excluded then Included the PIR & the interview process completed.
Installed the openLuup Z-Way plugin (master), followed instructions.
Bingo!
Neat.
A good practice exercise for me, but turns out to be possibly temporary.
The mentioned mini-PC options in this thread are drawing me to a more reliable solution.
@mrFarmer, thanks for the tip, if I stay on the Pi3, I'll definitely add the SSD drive.
Best,
DCMChrissy