14" or 15" in front?

Hey guys,
I am getting American racing outlaw I rims, the smallest width they come in is 7". You can get 14" by 7 which has 4" backspace. Or a 15" by 7 that has a 3.76 backspace.
I was planning on getting 205/70r15 or 205/70r14.
Some people seem to think 7" may be to wide on my 74 duster.
Thoughts on what one I should try?
I have currently a 14" rallye rim with a 205/70r14. Not sure of width or backspaceing. I'll be taking the rim off later today and checking.
Thanks
Richard