I grew this one (from fem seeds) earlier this year. I only sampled the "old school" maui from the seventies once in my life, but I was a different person then (hadn't tried nearly as many strains at that point, and didn't smoke much at all either)...but I doubt it's the same thing. I wouldn't say it's a poor representation of Maui Waui (it's still a good smoke,and I too still have some in my stash that I save when I want a slightly different effect than some of the other strains that I grew at the same time. It was my favorite of the three, but one of the others (Sweet Seeds Sweet Tai) was a better producer, so I have much more of it left to consume. If I had my choice, I'd smoke Nirvana's Hawaii Maui before the Sweet Tai...but I'd also choose a few other strains that I've grown in the past over the MW.
Bottom line, imo...it's worth growing out (esp since Nirvana's prices are relatively good), but it's not quite up to par to the Maui from the seventies, so if your dad's got high expectations, he might be a little disappointed.