@Bill_Reynolds - seems like you are close. If you use the property update API (PATCH) the property name goes into the API URL:
https://api.hubapi.com/crm/v3/properties/{objectType}/{propertyName}
The parameters are likely to be something like:
{
"groupName": "dealinformation",
"options": [
{
"label": "Option A",
"value": "A",
"hidden": false,
"description": "Choice number one",
"displayOrder": 1
},
{
"label": "Option B",
"value": "B",
"hidden": false,
"description": "Choice number two",
"displayOrder": 2
}
],
"label": "D-Tools Project",
"type": "enumeration",
"fieldType": "select"
}
Happy hunting!
Steve