To restore the neck. You have to find a hard round piece of wood, exact diameter of the inner neck, plus 0,5 mm, with a tapered front, lenght about 75 cm, knock the wood in the case, fix it with the protuting part to p.e. a work bench (not the kitchen table, trouble will be there) and start hammering and pressing the brass back tot the diameter, believe me, it will take time. It helps when you anneal the brass before starting. Also, i made two wooden clamps, inner diameter=outer diameter of the stright part of the neck. With the inner piece installed, you can start pressing with these clamps towards the mouth of the case. I used two piece of threaded steel, M12 and used a heavy wrench to tighten the clamps together arround the neck. Together with hammering with a "dead-blow hammer"do not know if this term is ok, and lot of time. after that, sanding back the outside, polishing it and you have a restored neck. Yours looks a bit disformed, however, possible to fix.
Right now i'm trying to find a method to remove the dents in the neck, or in the lower part. Hard time to find out how to start. Today i tried to solder the mouth airtight, by use of a less diameter shell inserted up side down in the shell, soldering the rim to the neck. Then installed and soldered a receptacle for the high pressure cleaner and filled the case with water and started the cleaner. Worked out for shallow dents, not for the more heavy dents, so back to the drawing board.
Projectiles, there are a few, 8,8 spgr L3/8, 8,8 sprg L2,8, i think 8,8 sprg L3,7 and there is a light shell for the WW1 8,8.
although more rare than hen's teeth, they show up.