I do not think you'll have any issues with the SM465. Yes, the NV4500 is nicer with the OD, but the SM465 is a robust transmission. As long as you're not dropping the clutch and beating it like a race car you'll be fine. Many other threads are highly supportive of the 465 for just about anything you can throw at it.
https://67-72chevytrucks.com/vboard/...e%20extra%20tq.