advice for 73 duster wheel combo?

was just checking out craigslist today and saw this:

http://sfbay.craigslist.org/scz/pts/1692954669.html

sounds like it would be a nice addition to my duster, giving it the cool 'raked' look. also, very period correct. anybody know if there would be fitment issues, such as having to trim the wheel wells, moving springs inboard? the backspacing isn't listed, so i might call him to find that out. i've never run anything other than stock wheels, so i'm not sure exactly what to watch out for.
if the above link didn't work, here's the rundown:

one pair 15x7.5 5 on 4.75" p235/60r15
one pair 15x8 5 on 4.75" p255/60r15
$200

any advice would be great, thanks!