I'd say it's a 383 then...I don't think its ever been out...
The car has a Stromberg 2 bbl carb on it so that makes sense...
Since this may be a cast crank 383 will the convertor also need to stay with the crank?
Were they internally or externally balanced?
I just pulled apart a 66 383 yesterday with an excellent steel crank and no offset weight on the balancer and no weights on the converter.
Thx...Dan