[novadude]

Yup. Depends on the cam. If you have a L34 or a mild aftermarket cam, stick with the B26. I don't 100% agree with full manifold source to the can in ALL applications. If the idle circuit in the carb is correct, you don't need a boatload of advance at idle. Also, make sure you are limiting the can to 10-14 deg of timing. Some replacement cans allow a lot more.

I have a 9.6:1 355 with a 217/225 deg @ 0.050 cam on a 108 LSA (104 ICL), and a B26 can works well for me connected to a ported source (no vacuum advance at idle - 12 degrees initial advance). You'll need to give us more info about the 396 if you want better advice on the right can.