Run Diesel Purge throught the injectors and IP only, pretty much useless to dump into the tank.
After sitting so long you are going to have algae growth in the tank and that can be pain. Do as Biodiesel300TD indicated and remove the fuel strainer, it screws into the bottom of the fuel tank, and rinse out the tank and clean that strainer. Use some algaecide in the fuel after that, you can find it at most parts store. I would use it in a few tanks, algae is hard to get rid of and the inline filters will show it. It turns that filters black. I would rinse the fuel lines out with some fresh diesel or some clean solvent or mineral spirits. Best to get that done before running the engine much. Then replace both fuel filters and the oil.