When you installed and timed the pump where the two cam lobes on the first cylinder pointing upwards? Did you notice? If not you may have your pump timed to the wrong part of the cycle.
The bottom pulley goes around twice compared to one turn for the cam and injection pump. I suspect this is where your problem lays. Those cam lobes on the first cylinder have to be pointing upwads at about a 45 degree angle each way.
Or to put it another way the tops of both of the lobes must be at almost equal height. Could be something else I guess but this is the first thing I would check by your description of what has transpired.
After carefully re reading your post I might be wrong but still I would inspect it carefully. Your overall description still sounds like the pump might be in wrong. What I am thinking is when turning the engine over to get 24 degrees you may have gone around once on the bottom pulley. This would be because you just were not aware and it could happen to a lot of people. Only if you are absolutly positive those lobes were in the correct position when installing the pump forget about it.
One more last thought. did you glance over to see if the mark on the cam was just a little off when you rotated the bottom pulley to 24 degrees and not basically pointing in a general downward direction? I am not trying to confuse you but just trying to supply enough detail for you to think about it.