I need your opinion. C3 Corvette Big Block with not original engine

Hello, I would like some advice about this Corvette here: the car is according to the owner in good condition as regards rust and so on. It is an original Big Block car with manual 4-speed transmission. the one here: 1974 Corvette However, and that’s exactly my question, Is the original engine not installed. According to the owner the engine was o. k., however, he wanted more power and therefore bought a 454 as a short block, which has a higher compaction, scooter cam and lifte r, and balanced rotating assembly. He said he doesn’t know what kind of car the 454 comes from. I asked for a cast number, but he meant he didn’t have a “cause the motor what covered” anyone knows what that means? According to his statement, he then mounted the heads of the original engine onto the short block. What do you think about this thing? I have such an entryable thing? He also has the original engine and the hood, but I don’t know how to send such a thing to Germany for justifiable pr What do you think about the car? I would like to go there on Monday, and look at it because I’m close to it right now. Is there anything that I should pay special attention to? Especially Big Block specific? The price is already good for a BB with Stick Shift. Marc