I have a 3 way ball valve on mine that split flow from a single pump to the kgb or the ibs.
I would also want the kgb working. It may not be necessary for you surfing, I really don't know. A lot of the older kgb bags are custom sizes that are no longer made. I was quote $450 to have one made for my boat. I think a lot of people just run the fly high tube sac. My kgb was leaking from around one of the fittings, and I was able to repair it using PL construction adhesive.