So....here's my problem. During the first of July, I purchased a restored '71 Z on eBay from a dealer/shop in New Jersey, and had it shipped to me down in NC. I had seen and heard this car at Carlisle in April 2018, so I wasn't concerned that I didn't need to see it and drive it in July (a big mistake!). I was sold on the pictures, and asked many, many questions before I made the offer and felt fairly confident I was getting a matching numbers car (that's the way it was advertised when I bought it). In late July, I noticed I didn't have any top end power (secondaries not opening up), so I took it to a local shop here in NC to look into it. Getting it to the shop was an adventure....it took 30 minutes to travel 5 miles...the lack of power had gotten worse. About a week after they had it, the shop called to say the cam was shot (more than likely it wasn't broken in correctly) and there was metal in the oil. I contacted the original seller to tell them what was happening and they agreed to send me $1000 to have the cam replaced, but that was all they would cover. My current shop was hesitant about just replacing the cam without tearing down the motor to make sure there wasn't anything else going on. That was the only way they would warrant their work. I ok'd the work and the fun began. Tearing it down, they found the cam was bad (not the original), one of the heads was cracked and dated after the build date. It also looks like the pistons, rods and crank are not original. So here's my dilemma. If you buy a numbers matching car, and upon further review, the internals (cam, rods, crank, etc) are not original, can you still say it is numbers matching? Furthermore, if the heads contain the GM part number and they are not date correct, can the engine still be regarded as numbers matching? In my case, the build date on the TT, and the date stamp on the block, trans and rear end all match. I'll have the work completed, but I'm just wondering how the new parts will affect the value of the car when it comes to selling it. Any input would be appreciated.