1990 French Beneteau Bilge Plumbing ??

[geoleo]

My new to me 19920 Beneteau First 41s5 has a horrid mess of dangerous bilge plumbing. Its French built. It has no seacocks. Has ball valves of unknown orgin and threads. These ball valve s have badly rusted handles-- one in fwd head broke when i touched it. The keel bilge drain is shared with the galley sink drain. The forward HT macerator drains back thru the y valve. The Deck pump-out for the HT runs thru the macerator without a y valve. That wont work ,might if macerator is running same time as pumpout running?? The fwd shower drain runs across the passageway to connect with the vanity sink drain just above the waterline lever. Is this typical with these era benny s ?? Can anyone help me identify the ball valves ? I want to change these to be safer. Thanks Benny experts.