Hi, I'm thinking of purchasing a 9k Muramatsu and a Lafin headjoint to go with it. Would the Lafin head fit in the Muramatsu body? From what I heard, adjusting the width of the headjoint can drastically change its sound.

A pretty good combination the body with this headjoint.

If it will fit you only will know by trying them. If they not, a good technician may easily fit them together.

And no, there is no drastic difference when you fit a headjoint to a flute body.