, Hello Kate :-)
It rather depends on what you intend to do with the boat. Littlewing made a significant point: Bruce King no doubt arranged things to the degree that it was practicable, so that the boat's centre of gravity lies in the fore'n'aft vertical midships plane when the tanks are at half capacity. Since the boat was to be a "cruiser/racer", that would have been the sensible thing to do. In that employment
there wasn't much tankage actually required.
If you want squeeze out the last `1/10th of a knot
going to weather
, and the last fraction of a point of weatherliness, i.e. if you want to race
'er, then sail 'er with empty tanks. I doubt that the CG will enuff for you to notice it.
If you want to cruise
'er, i.e to load 'er to the gunnels, then fill the tanks where they are. I doubt that you will notice any shift in the CG. She'll trim just about the same, but with an extra 500 lbs of clobber aboard (tankage plus other cruising gear) she'll not be quite as fast or quite a weatherly, but does that really matter for what you want to do?
I think she is a lovely little boat, and among the best of the little hybrids that were created half a century ago when every Tom, Dick and Harry suddenly had to be a sailor:-). I think that for many, many uses, such as summer cruising in the Salish Sea and beer
in Vancouver's English
Bay on a blowey Wednesday evening in the autumn, she's the cat's pajamas. So don't even worry about the tankage. Back, that half century ago, when such things were of concern for me, I reduced the use of potable water to the time honoured ration of half a pint per man per day. It can be done :-)
Additional tankage for a boat such as this is called a "jerry can" - but do make sure it's a brand new one. Using that, you even have that new-fangled wonder of wonders: Movable water ballast :-)
All the best