You are SO far beyond me I hesitate to respond... I can't add much, but I'm intrigued by what you're shooting for.
You can get the rectified birch tar oil and Cade oil at this site:
I haven't smelled unrectified birch tar oil so don't know if the phenolic component is less or more in the rectified, but rectified IS the way you want to go for fragrances.
A floral fragrance note that is supposed to go well with the smokey Birch tar is Cananga flower, but I don't have personal experience with it, so can't verify that.
Copaiba Balsam EO has a strong coumarin (hay) note in it, and is inexpensive as far as EO's go. I love this fragrance on its own, it's quite wonderful, but in a blend it's been a little difficult for me to meld in because of its balsam and hay quality. In a masculine accord it might work very well, though, for that slightly sweet, musty note.
Let me know what you end up with.