Hi,
I wasn't going to reply, because I don't have bullitts. I've been considering them, because I love the look.
Anyway, I would recommend you look at Dodgestang's wheel/tire size and backspacing chart. It's been posted in several threads in the past week. Sorry, I don't have a link handy to paste here.
It seems that there aren't very many 69/70 owners here. Kinda sucks to post a question and nobody replies.