people will argue with me but 300zx are a hunk of junk, for a v6 it makes shitty power. 240s and 300zx's biggest problems are blowing head gaskets. look again, most of them for sale are because of blown head gaskets. the only reasonable 300zx are the twin turbo ones.
dropping a motor into a civic is easier than opening a jar of pickle. first time around with very little knowledge took me 45 min to pull out and 2 hrs to prep and drop new motor in.
forgot to mention, honda and acura motor are identical. you can plug and play an acura motor into a civic.