The most obvious are the cross bolted main caps (3 of them) down by the
oil pan. Some people have put bolts thru a 428 to look like a 427 so beware! You should also notice a 427 Side Oiler with a bulge running the length where the freeze plugs are. The for sure way is to look at the casting numbers & cross reference them to a Ford engine book.
Catch ya later
Ed