You don't say how much experience your dad has. As others have pointed out, the community standard here in the Keys requires "recent verifiable deep diving experience" to put open water divers on the deep wrecks (Bibb, Duane, Spiegel, & Eagle).
As an open water diver, your dad qualified to dive to 60' max, in conditions similar to those he was certified in. If he wants to dive deeper, he should (IMO) continue his diving education.
He has in excess of 3000 dives. Back when he was certified there was nothing more than Basic open water certifications. He is certified to 130, that was the limit even back then. We have been all over the world diving together and yes he sometimes get odds looks because some have never seen a Basic card but he likes it and he has never been denied diving. He is now 62 and has no interest continuing his diving education.