fuel water separator

Hi, I am a happy new owner of a V20, 1982 with a 150 hp Black Max. I want to install a fuel/water separator. What size/capacity would be recommended? Thanks, Larry

[spareparts]

just use the regular one(merc, sierra, mallory, etc) that uses the Mercury(1/4 npt or bigger) spin on filter, if you want more capacity, leave enough room under it to put a Yamaha filter on it(its about 4" longer), or you can use a Racor replacement element with the clear bowl to inspect your filter, just don't get used to draining the boawl and not changing the filter