Hey JustinOlson, here are few Z's I have found on craigslist while browsing. You may or may not have seen some of these, but I thought I would give a heads up anyway. One looks to have a "ragtop". It looks pretty good, but if you are going for over 1000+ hp, I'm not sure it would be a good fit. It does come with a complete spare (supposedly running) 280z motor....
1972 Datsun 240z (fi 280z motor w/ spare) - $1500
http://seattle.craigslist.org/tac/car/573174959.html
This one states it is a signature series. States it has 81k original miles too. Look like some rust on the bumpers, maybe more? Price seems steap for your needs, but if it is rust free could be a good find....
1970 Datsun 240z signature series - $5500
http://seattle.craigslist.org/skc/car/573123966.html
Here is a "74" that states it has rust free sheet metal except for the roof and surface rust. Pretty cheap and is somewhat stripped down. Could be useful for what you are looking for?....
74 260z part car - $300
http://seattle.craigslist.org/see/car/569994908.html
Here is a "72" not much info, but states it runs and title in hand. Could be worth looking into....
1972 datsun 240z - $2500
http://seattle.craigslist.org/sno/car/570016493.html
I hope at least one of these may help. There were a couple of others as well. One looked really good, but had a 8,800k tag too. Good luck.....