but I'd like the text description to display for all entries since Day 1
A bit confusing to me. Text description from where, the table? Have to think so since the way you describe the combo behavior (and say it's all good) makes me think so. Then what you seem to be describing is the view of a table where a key value is a foreign key from another table (which happens to be an autonumber) and that's not very informative. It's not supposed to be really. Unless the foreign key is a text field, that's what you'll get, but this is OK because you're not supposed to be poking around in tables anyway. You should have a form based on a query that provides the deprecated values, including text descriptors.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.