I've been using those aluminum bodied carbs for quite a while, they're developed by quick fuel and proform and when they get debugged holley starts selling them. They are great carbs, esp the proform street carb which is basically a race carb with a nice electric choke. I've been using them for about 3-4 years and the only issue is that they are more sensitive to heat so you need to isolate them with a wooden or resin spacer (i'm not a big fan of the plastic they are now using and calling 'phenolic').
And, i agree with Dave, the 950 is too big. Jetting a big carb down is problem solving not tuning. The 502/502hp gm crate motor comes with an 870 carb - roughly 10% smaller than your carb on a 15% larger engine. A 750cfm would be just about right.