Rim and tire fitment question

If you ordered a 7 inch wheel with the same backspacing then the extra 1/2 inch is on the outside of the wheel toward the wheel lip where you said you only had a 1/2 inch of clearance! I've never been able to fit 7 inch wheels on my 70 darts unless I moved the springs against the frame with a kit and then had the extra width on the inside of the wheel taking up the extra space that was made.