they will fit but be outside the guards unless you have flairs.. (which by the looks you don't have) they are just a bit too wide
And depending on what your front struts are they may hit the strut or the tire may hit the strut and need spacers which are not legal
The best fitting wheel for you datsun will need to be a zero offset or up to +30 (positive) not negative (backspace), then it depends on your strut and the tub on the rear.. if its a ute more then 15x7 will probably hit the inner wheel arch needing spacers to clear..
and if the car is lowered you will need at least 175 or 195 low profile to fit under the guards and not scrape when turning
check out these links for a better understanding of how they will fit and what offsets
http://datsun1200.com/modules/mediawiki/index.php?title=Rimshttp://datsun1200.com/modules/mediawiki/index.php?title=Offsetfender pulling
http://datsun1200.com/modules/mediawi ... .php?title=Fender_pullingtires
http://datsun1200.com/modules/mediawiki/index.php?title=Tiresjust as a note i am running 15x5.5 with +25 on the front and 15x6 on the rear with +35 and they fit clean in the guards with 175/70 and clear the strut and leaf's perfectly with room to spare
Generally you want a +30 offset wheel for tires up to 175-wide but a +25 works fine
I also have stock 1200 struts not lowered and just refitted leafs and fit fine