My buddy put one behind a 69 460 with a 268H cam. It was in a 71 Mustang.
He hammered it pretty hard and it did fine. Never had any real tire under it, but he also drove it harder on street tires than most too.
I wuld say the truck bell is right on too, he used a 400 truck bell which should have the same small block depth in 460-land.
---------------------------------
- 70 Fastback Mustang, 489 cid FE, TKO-600 5 speed, 3.70 9 inch
- 71 F100 shortbed 4x4, 397 cid FE, headers, Street Dominator, 280H, 5 lug Dana 60, 4 speed