This is incorrect. N1 pumps have bigger gears than the standard pumps, however due to this there is less clearance at the lowest point of the gear cutout. Standard pumps won't pump as much, nor at the same pressure as the N1 or aftermarket pumps, however they won't die as easily as an N1 pump.
Check this pic out
http://www.skylinesaustralia.com/forums/index.php?app=core&module=attach§ion=attach&attach_rel_module=post&attach_id=215653
Notice the thickness on the outer section where the tooth slides into? On the first two its rather thick, 4-5mm it looks like. Check out the thickness of the outer edge of the N1 pump - its thin as, 2mm or something.
When the revs go over 8000, that is what breaks. You won't have this problem on a Jun, HKS, Tomei, Nitto or even Nismo pumps as they weren't manufactured with such a small amount of metal holding those teeth in..
If I was you, buy the built engine with the n1 pump, and when finances permit it, then take the engine out and replace that pump with a Nitto (or brand of your choice).
In either case, just keep the revs under 7500 to be safe and if you want to take it to a track, then change the pump
-D