Orange line to Reseda and then there are a few lines up Reseda that will take you to Nordhoff. As for reliability, unfortunately Reseda can get pretty clogged up (especially going back in the afternoon)... and I'd guess you would have to budget 1.5 hours for the trip. But I don't know of much better options... since all of the bus routes pretty much go vertically and horizontally you are stuck with routes that go too far out of the way and change at least once.
Metro Maps
You can get some other route suggestions with
socaltransport.org | Metro Bus and Rail Trip Planner for Los Angeles and surrounding Counties
For instance From: 'red line north hollywood' and To: 'nordhoff and reseda' gives a few other routes, but I wouldn't trust any of those 30-60 min time figures they give at all unless you tried it yourself.