FYI - Got something to work!
Can see my VM is in VM overrides with correct setting after running.
Code snippets below (vm_moid is the moid from vmware_guest_info output)
vm_config_spec = vim.cluster.ConfigSpecEx()
vm_config_spec.drsVmConfigSpec = [vim.cluster.DrsVmConfigSpec()]
vm_config_spec.drsVmConfigSpec[0].operation = "add"
vm_config_spec.drsVmConfigSpec[0].info = vim.cluster.DrsVmConfigInfo()
vm_config_spec.drsVmConfigSpec[0].info.key = vim.VirtualMachine(self.params.get('vm_moid'))
vm_config_spec.drsVmConfigSpec[0].info.behavior = self.params.get('drs_vm_behavior')
vm_config_spec.drsVmConfigSpec[0].info.enabled = self.params.get('enable')
try:
task = self.cluster.ReconfigureComputeResource_Task(vm_config_spec, True)
changed, result = wait_for_task(task)
. . .
