it really is not that hard.  i made a set exactly like those, and they looked damn good.  once you cut em open you'll see that if you just push the latch down they open, so weld an extension on em and then cover it with sheet metal with a little slot for that rod you welded on to stick out.  just push em down and they open.  thats the easiest way, but you could also mount the stock inner latch horizontally and bend the rod so they work like that.  anyways, dont be scared to dive into projects like that, if u have a beat up set of doors then u shouldnt be worried and ull never learn if u dont try.  just lay a piece of masking tape on the doors where u want the cut and follow the tape line.