Wait for Season 2 and see. Season 1 is a take on an origin story and it sets up Mason, Street, and Drake together by the end of the season. They are aiming for a 'grittier' style that combines hard-boiled detective noir with courtroom procedural. If your dad is willing to watch it with the understanding that this isn't meant to be a replacement but an adaptation in an adjacent genre, he might enjoy it starting straight from Season 2.

There are some big differences like Paul Drake being a black character in the 1930s which will have the new show play out very differently, but based on reviews I think it stays true to the character while finding new nuances to explore rather than just rehashing older material.