Sorry about getting the name wrong. I'll blame it on being old.
If I knew where the 428 came from I no longer remember. I'm sure the truck came from the factory with a 360. But that guy was always having motor trouble and collecting spares.
Back around the same time I had another friend with a Shelby Mustang GT-500 KR that had a 428 in it. That one was original.
And while I'm happy to offer help on restoration I'm more the hot rodder type, so you'll be reliant on others for accurate details of what it was and needs to be as you restore it.
If you haven't already found it, you'll appreciate the information available in the
Restoration Pack.