Your best bet would be to save the 17" chrome 7-spokes, as they are a tad rare, and eBay a set of 2003 - 2005 CTS rims in the same pattern, then send them out for either a black chrome or powdercoat job.
Those 17" chromes are around $400 a pop, used, and scary priced New Old Stock (NOS).
Take a look at CTS and Seville in
www.wheelcollision.com, click on the little pic next to the wheel of interest, and surf their powdercoat and black chrome listings. Start to finish, a GOOD job, wheels and all, will run around $1800.
Also, take a look at
www.ezaccessory.com and surf to lug nuts, acorn, bulge, chrome,
through hardened, 12x1.5. Easier and better looking than the 2-piece stock units.