http://www.japaneseclassicsllc.com/
^I'd take any of those S-Chassis for 5k more which will have less miles and less engine swaps than the car you are looking at. Just because it has an engine swap does not make it less of a shitty 240SX.
If your shit has an M&M in it, does not make the whole object a bag of M&Ms; its still shit.
Imported Nissans are going to wreak havoc on 240SX prices especially if the buyer has money. 6K for a 240SX with unknown miles with an engine swap with unknown miles or 9K for a silvia/180SX with low KMs and factory engine? Hmmm