i would look into the 505T --- the 505A is going to be longer and more angular, imo i believe you would be better off with the 505T, then you can adjust the cover if you desire.
715C would fit just below your Nomad Dagger depending on everything being the same. Surface you'd need to knock off FF polish and make 4000 abralon so you wouldn't get the over/under. Good length and roll depending on ball surface, layout, and your stats.
505T has a stronger cover than 715C so that ball is out unless you drill a lot weaker. 505T has more strength total hook than a Nomad Dagger all things being the same.
My Visionary Gladiator Pearl has much the same strength & ball motion as a Dark Star. I had a 505A though weaker drilled has a stronger cover the both the dark Star and Glad Pearl but it has too angular a movement to be a good ball above the Dark Star. At least that's what I have found.
715C and have driller get good ball layout and surface to do what you want.
Scott