I can't help with advise on how to do the oil pump, I doubt its easier to remove the whole engine though.

I am only chiming in to suggest youget a service manual for your model. I don't know if the dealers carry them back that far. There are other sources, like ebay. I have purchased from this site
http://www.repairmanual.com/motorcycles/1988/24

there are always questions about Haynes, Clymer, etc... I think, in general, everyone seems to thing the HD branded manual is the best.

 

i just went out and got one tonight, cost me $58 and about 50 miles, but thats the only dealer i could get it at. VERY informative!

 

good move... it will be your favorite read. I'm not a mechanic, but I do my own service, and the manual has proven its worth over and over. Even for basic service where I don't need to read the step by steps anymore, I still look up the torque specs