If you can, definitely get us some pics so we can see what is going on. How far off is the pin from where it should be. Springs are very hard steel but a new center pin hole could be drilled in each pack if the length of the springs is okay. Would not be the easiest thing to do though.
Another option if the spring length is okay, and if the center pin location is not too far off would be to use the Zero Rate blocks from
www.offroaddesign which can relocate the centerpin I think 1". Course that would make your rearl lift slightly higher than the front lift. Probably not noticeable though.
My guess is BDS and the other company haven't dealt with the 67-68 and just screwed up rather than knowing about the problem. I've heard good things about BDS so lets hope they take care of you. You put a lot of time into installing the springs so the owe it to you to go out of their way to make it right.