If it needs head work the money can pile up quick. When I worked at the machine shop it wasn't uncomon to see over $1k for labor, parts and machine work.

On a side note: do you know if the new maxima engine bolts into a 350z? I got a friend that has a whole 2003 (might be '04, but I can't remember the year) swap. He wants like $1200 or something ridiculously low for it.