Don't make it harder than it is. Just take your time and cipher - don't take what the experts are telling you as absolute. Mock it up and measure. If you can't get a feeler gauge between the oil pump and dist gear, use modeling clay like you would to check valve - piston clearance. If the gear is bottoming on the pump before the flange hits the block measure the gap at the flange. A little gear marking paste or Prussian blue should give you a read on the gear mesh, if you can't eyeball it. Spend a little time measuring and you'll know where the problem is - if it still exists with the new parts.
Don't panic and don't give up.
If it doesn't look like this, keep modifying until it does.
http://chuckthetruck.homestead.com/chip.html
