to add to what chipmunk said, if the truck had been a factory V8, the vin would have a leading
V on the door tag and title, as yours doesn't, it had a 235 from the factory - another way to spot a factory V8 [55-59] is that the
front mount "birds legs" attached to a bracket riveted to the front cross member [pic shows a bolted on replacement], they didn't use the side mount points available on SBC blocks .... a '59 would also have had a metal fan shroud
similar to this [adapted from same era car]
Bill