Here in Canada we follow the same guidelines- we are also trying to keep between 120-360. I personally like to keep my daughter's levels a bit lower (between 120-260) but my doctors/dieticians/specialists do not seem to think that is medically necessary but I've found that my daughter (age 1) is a different child with higher levels- the higher the level the less sleep she gets, the more irritable she is and she doesn't seem to progress as well.
We will never introduce meat or dairy (or regular grains) to our daughter if we can help it. She is also CPKU and we feed her specialty foods and fruits and some veggies (although everything is weighed /measured/counted) . I'm not sure if it matters if it is mild pku or hyper as they are treated the same- for my daughter her first level was 377 and then at 7 days it was 1100.
She is now transitioning to her toddler formula which has more protein than the baby formula so at this moment i'm not exactly sure her total daily protein (she gets a bit of baby formula, a bit of toddler formula and a bit of breastmilk each day ) but in solid foods she is getting 80mg phe per day.