Look at this application chart from Comp Cams. You'll see duration at "advertised" and duration at 0.050" lift. Advertised duration is checked at a tappet lift of usually around 0.006", while 0.050" lift duration is checked at....you guessed it....0.050" tappet lift.

I don't know what size motor you have there, but my best suggestion would be to call your favorite cam grinder on the phone and talk to one of the tech guys there. Have him recommend a cam for you, 'cause the one you have is gonna be a nightmare.