i don't like being killed as kha before ending the jump by the adc

To be honest... if you jump at an ADC, and die to them THAT fast... you're probably doing something wrong.

I don't like dying to kha in less than 1/2 a second from stealth when he has a gap closer that's a mile long. :P. I think adding that would be a big mistake. Try to use your ult to be sneaky and get up to the enemy if they're killing you before you can get to them. Armor also helps quite a bit VS ADC's. Being an assassin doesn't mean you're unable to buy defensive items; often times living to kill the enemy is worth more than that little bit of extra damage from a different item.