Thanks for all the advice guys!
Some of the intake pushrods are slightly bent, however most can not be distinguished from the ones on the exhaust side. I would have replaced them anyway when installing the cam, as shorter ones are required with the retrofit roller lifters.
I will order new intake valves, check everything carefully and cut the valve reliefs bigger if all parts are ok.
One thing I noticed is the timing chain seems to have a lot of slack for a double roller with less than 5000 miles. Looks like too much to me:
Of course this is far from ideal when piston to valve clearance issues exist.
I was thinking about a gear drive, but a quick google search revealed that most people seem to favor timing chains.
Also the leaky valve seals are on the exhaust side too:
Consequently it might have nothing to do with the bent valves. How is it possible the seals leak like this after only 5000miles? Valvetrain geometry is ok, the shiny spots where the rollers contact the valve tips are exactly in the middle of the stem.
I'll have to take the credit for the mistake with the intake valves, but besides this I'm not too happy with the quality of the parts...