Heck for 4K you can one not wrecked one and drive it for a month or two to make sure your happy with the preformance. Then do the swap. (40K motor assuming no one lied, LOL)

1998 Camaro Z-28 $3800

"Up for sale is a 1998 Camaro Z-28....Vehicle is in great condition for year and mileage on the body. I have had the car for almost 3 years now and it has been a pleasure to drive. Oil has been changed every 2500-3000 miles . . .During my time of ownership I have replaced a few things on the Camaro. . .I've had KYB Gas struts /shocks installed about 3000 miles ago, Front Drilled Rotors with Ceramic Break Pads installed about 5000 miles ago, Rear Drilled /Slotted Rotors with Thermo Quiet Ceramic Brake Pads installed less than 200 miles ago.....I had a CD /DVD player with JBL 6.5in 3-way Speakers professionally installed by the Geek Squad about a year ago . . .When I bought the Camaro it was stated to me the engine was rebuilt at around 133,000 miles with stock parts for the LS1 other than the camshaft and springs coming from an LS6 engine. The vehicle has about 173,000 miles on the body."