A place I'm going to have one of my Zs done up is a place called Wendell's Auto Care, in Lakeland. I've seen a few of the cars he has done (the guy does a lot of insurance work/collision repair) and I haven't been able to find any seams on the bodywork or paint, cars look like they weren't ever wrecked.
He quoted me $1500 for paint and rust repair (putting in new rockers, quarter panels). Might be worth giving him a call, get a ballpark price.
I don't think he has a web site so per his card:
JR
1350 Olive St.
Lakeland, FL 33815
863-899-9602