more big-headed / bigger-headed?

[riglos]

Hi guys!
I was just wondering about the use of comparatives and superlatives with compound adjectives. Which would be the correct version?

1. He is more big-headed than his father.
2. He is bigger-headed than his father.

The question applies also for such adjectives as big-hearted, well-disposed, well-built.

In the latter case, which would be right?

3. He is better built than his partner.
4. He is more well-built than his partner.

And, as regards the superlative construction:

5. He is the best built man I've ever seen.
6. He is the most well built man I've ever seen.

I look forward to your replies!
Thanks in advance,

Mara.