Honestly I'm not a fan of the "bumpside" moniker, as I grew-up with these trucks, and to my ears it all just sounds so..."trendy". But the younger guys call them that, so....
Anyway, I'd love to see the door tag on your truck, as the 429 wasn't offered in the F series trucks in '70. "Special Order"? Possibly, and while I've seen some pretty rare ones recently online, my guess is that the 429 was swapped-in.
Feel free to shoot me a PM, as I'd love to decode that tag for you!
(Edit: Oops! Forgot to add a picture! Example of door tag below.)
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