Check for timing marks on the Pump mount to front engine cover. Usually the outer mount will have an elongated hole. By this mounting hole will be where you find a timing mark.
Usually the engine should have Number one cylinder at TDC. There might even be a way to lock it there (Pin access hole in block to flywheel)
If the front engine cover has an access plate directly in front of the injection pump most likely there is something you need to take apart behind it or timing marks or it would not be there.
I would get a service manual. And take plenty of pictures as I took it apart.
line up timeing marks on pump window then check flywheel bolt for tdc...r&r new inj pump,play with timeing by rotaing pump it self on the sloted inj pump bolt mounts
Yes i have done this more than once...Randall