Typical tight spots are around the trans to block bracing on the passenger side, and the steering and starter motor on the driver side. Also, once you install the headers, I highly recommend a front antiswaybar, which will cut down on the amount of pavement your drivers side header gets to meet on a direct contact basis.
If you have not yet purchased the headers, stepping up to a slightly higher price range will get you a much better fit. My Hedmans far outdid the "blackjack" headers I started out with years ago. Also, swapping to the smaller Nippendenso starter found on the Dodge trucks from the 1990's will greatly improve your fit issues.