The valves your referring to are the
main control valves to put air onto each of the ballast tanks. The
valves called out aren't available any longer as far as I know. It
really doesn't matter at all what type of valves you use to replace
them. I just used quarter turn ball valves. I followed the schematic
in principal but didn't use the exact components that were called out
on it. The important thing is that your valves are of sufficient
pressure rating and that you have two valves for each hull penetration
as called out. One valve for control and a second for emergency.
I think you can see some of what I used in the posted pics of
"Persistence." Also I used stainless fittings and valves.
If I can help more, just ask, Dan H.