I would assume that the 52 degrees overlap is based on 0.006 lift and not 0.050 just like their duration numbers (or whatever low lift number they used). My Oregon cam card shows 42 degrees overlap.
No, the 52° overlap is based on the seat-to-seat duration numbers and matches with the lobe separation and duration figures as you can see in my charts that I posted above... I used data straight from the factory service manuals for my spreadsheets...