Yea.. tires for 20s arent that bad.. and if you wanna see really suck, then going staggard and losing the ability to rotate your tires is just the way to do it..
Even if the vette wheels did fit.. you will have to run them right where they are so when the insides wear on the front , there is no rotating them to the back and getting 25k more miles out of them... its throw them away.
Nexen Nakkang or Achiles are all like 100$ a piece and for $150 you can get Falken Nitto or Kuhmo ....18s are almost the same price and 17s are about $25 cheaper per tire.
Finding a set of used tires and wheels might sound cheaper on the face.. but well.. like the Nexens are rated for 60,000 miles.. with proper maintenance and rotation... thats 4 years... $100 a year in tire cost... vs those used ones who will last who knows how long..