You will likely never find one of these OD units but it would provide the highway speeds with the stock gearing. Somewhere near 70 mph @ 2500 rpm.
https://www.jalopyjournal.com/forum/threads/truckstell-overdrive-model-101-vs-103.783592/The connections for these are far more complicated then the Borg warner OD on the open driveline trannys. There is a closed drive line OD designed for Model A Fords that might be adaptable.
