Porter, the front end on my '66 is darn near 73" from outside of rim to outside of rim (standard rims, not sure of any offset). Hope that helps.
I know that using the lower control arm and spindle will increase the width about an inch, but doing this will require you to remove all the shims from the upper control arm, because the later model lower control arms are mounted closer together at the crossmember. Even if you did that, the width will increase about an inch (know someone that did it).
I changed the entire crossmember out (check out my progress on my website); haven't gotten any measurements as of yet, but I expect the width to increase some. If I make a junkyard run tomorrow, I'll see what the width of a '75 is.
