1970 Camaro BIG Problems +++ please help +++

[JJEH]

Okay, I just got a call.

All the rusty $hit is gone, the workshop fixed all.
Suposedly to the "agents" (Germann Company) expense...

Now the only matter is the engine.

My brother said he wants the ZZ3 engine but it's just a 305ci in.

The seller told the "agent" it's a 350ci in with the ZZ3 Kit.
The Kit brings more ci and more HP the seller said.

My question is, how can I absolutly identify the ZZ3 engine?
And what is the Kit for?
How can I tell the different between kit and engine?

Thanks Guys for your help!!!

BTW: There was no contract between seller and "agent..."

[JJEH]

Here is the original classified from the seller.
I got it from google cache.

1970 Chevrolet Camaro

And here are the different statements:

The German workshop (who fixes the car): It's a 305.

The seller: It's a 350.

The German "Agent" (who bought it): It has the ZZ3 Kit, so it has 350ci.

My Brother: "I want the ZZ3 or a comparable engine (350ci, 345hp)."

The rust part is solved, the workshop did all the work. And my brother wants that car, but not with a weak 305, because the reason for this purchase was the whole packet... incl. the ZZ3.