When I swapped from an open rear to a posi, I removed the pumpkin from the axle housing myself and re-installed the finished product. Besides that, I had a local specialist do all the ring and pinion work for me. He only charged me $90 of labor! Of course, the parts cost me another $400, but for $90, I had an experienced rear-end specialist set everything up for me. He setup NASCAR 9 inch rears for years, so it was certainly $90 well spent.
This is something you never want to mess with again, have someone that really knows what they are doing setup the ring and pinion for you.
Just my $.02