Hi Alex and welcome from Idar-Oberstein! That's southwest of Bad Kreuznach in the Oberpfalz.
That engine is most definitely NOT original! Thebiggest engine Olds put in a Cutlass thru 1967 was in the 442, and it was a 400 cu in 345HP. That's what mine is & it's a matching number VIN, motor block & heads!
Having said that, if you want to register it as an "Oldtimer", you should be able to use the data from the 400 cu in, since the German inspectors don't know much about the cars.
Am Beispiel meiner: Serie: 350PS, 6555ccm, 597 Nm.
Tatsaechlich: 429PS, 6735ccm, 640Nm! The motor has been completely rebuilt and maximized with performance parts available during that period!
Wenn's hilft, kann ich die Daten mailen! Komplett m. Kopie v. Brief/Zulassung!
Dies wuerde vermutlich ein Einzelabnahme unnoetig machen! Spart sehr viel Geld!
Also: check out
www.dr-mustang.de. They not only deal with Mustangs & Ford, but they have sections for all US cars, plus they have an entire section of tips on importing & getting the car ready for inspection!
Their annual meeting is 25 & 26 July in Oberhausen at the Centro Mall. Stop by! I'm "Z28 Heritage" on dr mustang.
Gruesse u. allzeits knitterfreie Fahrt!
Ralph