Another good compromise in 30cal and one that seems popular even in the magnums is the 165gr bullet weight. Particularly in the smaller 30-06 case this weight keeps the velocity up giving a bit more of the shock effect which works well on the ungulate animals.
Although the 150gr bullet weight seems to work okay on deer size animals in the '06, these bullets always seems to me to be a bit stubbie in the 30cal guise and probable compromises long range performance a bit, which may or may not be a consideration with your O/U.

Sounds like a good project for you to develop a load and regulate the Tikka/Valmet.