Hello
It really depends on this magazine, what level of quality they expect and the kind of content you are going to capture...
The "pixel" quality of the R-D1 is excellent and its photoraw 13.5MP interpolated output is also of very high quality for enlargements; it does not introduce artifacts (obviously it does not create detail it just provides an optimized upsizing for printing). So I can generally go up to A3+ or sometimes A2 on my epson 3800 even after cropping.
Now the content is also a critical parameter: a street photo is more permissive as detail is less critical in general then say an architecture, a portrait or closeup shot. With these A3 is probably the max "acceptable" limit, without cropping.
In any case a rangefinder is the best tool for street photography especially when you don't want to be caught or interfere with what you are capturing (ie when you should not be seen as the photographer). So for this kind of work technical quality is not IMO the most critical parameter and shots from "grand masters" shows always detail lost in the grain (high iso), imperfect focus, motion blur, etc. But if you are to be seen as Mr. Photographer, you can go with a big 24MPO DSLR plus bazooka lenses ending up with better technical quality for enlargements.
It is worthy ot note that for high ISO the R-D1 is great and gives higher MP cameras a run for its money including the M8
Hope these help in your decision. But the best remains that you get a good RAW sample file from a R-D1, enlarge it with photoraw and then give it as a sample to the magazine for acceptance.
Philippe
www.flickr.com/photos/pmat
http://streetphoto.free.fr