A good line drawing of the Krupp 8.8cm L/30 would help. It's my understanding most of Krupp's documents were destroyed after the War.

Krupp survived by owning a large share of Bofor's and moveing thier people out of Germany.
The WWII version of the 88 does share some details but one will need to study any images of the WWI U-boat Guns to do a good model.
As it's a player used Gun it will require better details then what would be done for non-player Guns.
I hope the images I've collected help.