My Dart has 14" rallyes. I like them . I will probably end up going to 15" versions but most importantly you need the proper centers. For 70/71 you should have the "sombreros" If you want to get picky the 71 version is dark argent silver.
I would also prefer the rallyes! The design of the rallye wheels is just awesome. But I have the same problem, it's damn hard to find the 70/71 14" rallyes in europe. I bought my Dart with the wrong one (72+), so I swapped them for some old patinated Cragars. Personally, I don't like big 17"... But it's up to you, and what look you want.;-)