comp 264s cam timing

OK guys I've hit a snag. I'm putting my slant back together after a rebuild and I'm having an issue with the cam. I'm not exactly sure of the problem since my friend is timing the cam but apparently there is something different about the key way and the van needs to be installed 6 degrees but the key way or something won't let it. Can only be installed 4 degrees. Then he said something about needing to drill the timing sprocket to make the holes line up. Anyone understand any of this? I need to talk with him about it but I'm not hood with timing a cam so I dunno much about it. Any help is appreciated.