How would you make the Black Dragons using the Chapter creation rules?

I've got some ideas, but I'm curious about your input. Also, would the DW even accept them?

Useful link first

http://wh40k.lexicanum.com/wiki/Black_Dragons#.UeGMV-Ahf4Y

Rules-wise? They have a pair of swords that don't take up a hand, possibly with the mono upgrade if covered in adamantium.

I'd give them +5 WS and +5 Str, though possibly only one of the stat boosts due to the ability to parry with their hands full, or maybe -5 Toughness to represent the over-taxing of the body due to unwise genegineering. Solo and Squad modes to taste.

As for service in the Deathwatch? I think it would depend on their Watch Captain and what Inquisitors were kicking about at the time. Easiest way I can see would be for one to enrole as a Blackshield and pass off his adamantium covered claws as armour customisations.

They do seem to be a chapter that isnt going to send its most identifiable members to Deathwatch....younger ones perhaps before the bone develops too much

Indeed. I wouldn't be suprised if many Black Dragons with more developed bones would be targeted as Chaos Marines by their brothers who may not be up to date on the Black Dragons' special circumstance.