As far as I know, no one makes an 8.1L carb mani. If there is one, it is brand new and I haven't heard of or seen it yet. Meaning, it would probably be shown here before anywhere else.
ASM has a stand-alone intake and ECM package for the 8.1L:
http://us.st11.yimg.com/us.st.yimg.c...d_1914_6425680
You would need the injectors and sensors from your other 496, but thats about it.
http://www.azspeed.com/