@billytwosheds Thanks so much for your inputs.

I am quite doubt the frame is from De Rosa as I did a quick research, some of the identical de rosa frame is not found on this bike.
First, I thought it might be a Japanese frame, but then i found out that the BB is Italian. I guess back then only the Italian builder would stick on with Italian BB, not others?

Where could I locate the date code on the campy parts?

The crankset is ofmega c/w torpado chainring

P/S: The De Rosa decals are on the frame surface.

BR.