Generally speaking there's no difference from it being a Nexus-based core vs. a Catalyst-based one.
I would normally upgrade the HSRP standby unit first to minimize things being changed at one time.
Just run the "install all nxos <image name>" command on the Nexus and watch for it to come back up successfully.
You diagram looks a bit odd. I would not expect the ASA primary and standby to both connect to Nexus interface Po1/VPC106. You also show VRF Inet only on the "B"Nexus, Is that correct?
