a plant based diet only means that you have a wide variety of veggies in your diet. It does not mean that you do not meat.
the idea is with protein is to eat at your maintenance level (~1 gm/lb of lean mass). That's it!! unless you are looking to gain, in which case you raise your intake as per your requirement.
The health aspect has more to do with the fact that plants would give you more fibre ('regularity', cholesterol, satiety, glycemic impact etc), they provide your essential micro-nutrients which keeps your body healthy.
you can get the same effect eating animal proteins as long as you take in enough plant foods to get fibre.
and thank god that your wife keeps organic stuff.