dont even need to remove oil pump. just the triangle brace behind drive chain sproket on left side, and one behind the the clutch basket, then remove the shifter shaft.  Impact driver is a must on these(thought i mentioned it, perhaps another posting) Dont forget the one bolt at back of starter in top of case, and the 2 allen bolts under oilfilter , get them through oil pan area, they are tiiiight.

The oil pump does not need to be removed.
However, the pickup screen in the bottom of the motor does.

Harbor Freight Tools has impact driver sets. I've bought them on sale for $3.00  You'll need one for a few screws. And a torque wrench that will go down to 9 ft lbs.

Would something like this work: http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=46978  

That's exactly what I have.