Moving to New vCenter Server 6.5

We are preparing to move from a Windows vCenter Server 5.5 environment to a vCenter Server Appliance 6.5 environment. We’ve tried using the VMware migration tool previously but ran into issues. An incident was opened with VMware with no resolution. Our current environment consists of two Windows vCenter Server 5.5 servers at two sites, Prod (on premise) and DR (remote). Each site has a ZVM running 6.0 U3 and the VRAs are also at the current version as they were automatically upgraded during the ZVM upgrades.

Here’s our migration plan:

1) Stand up new vCenter Server 6.5 appliances
2) For each ESXi (host one at a time)
a. Power off VRAs, delete VPGs
b. Disconnect ESXi host from vCenter 5.5
c. Add ESXi host to vCenter 6.5
d. Upgrade ESXi host to 6.5
e. Repeat for remaining host in each cluster

Two questions:

1) Do we need to uninstall ZVR 6.0U3 from both ZVM VMs at the sites and reinstall because of the new vCenter Server?
2) If not, after the hosts are moved to the new vCenter Servers, can we power on the old VRAs and recreate the VPGs? Or should we delete the old VRAs and create new VRAs because of the new vCenter Servers/UUIDs?