tense related

[sane]

Is this sentence correct:

I would never believe that such an all round man with so many talents developed to such perfection lived in Milan, had I not known him.

[Raymott]

Is this sentence correct:

I would never believe that such an all round man with so many talents developed to such perfection lived in Milan, had I not known him.

It's awkward.

Had I not known him, I would never have believed that such an all round man with so many talents developed to such perfection [had] lived in Milan.

If I didn't know him, I would never believe that such an all round man with so many talents developed to such perfection lived in Milan.