Soy made a scrappy little scrap bow for me where the back of the bow is the growth ring in transition between orange heartwood and creamy sapwood. Part of the ring is orange and part is a pale buttery yellow. The FINAL arbiter on what ring you should use is whether or not that ring is chased to a fair-thee-well, flawless in execution, and has your utter faith.
If you hate chasing rings, I can only urge you to suck it up and put on your best game face. Screw up tiller, and you can fix it (albeit with a lower poundage bow, likely), but if you screw up that growth ring, you have scrap! I'm lucky that way....I LOOOOVE chasing a growthring, and the more tedious it is, the more my thoughts simply fade away and I become a spectator watching my hands slip off finer and finer curls until I am surprised to see the other end of the stave with a gorgeous growth ring laid out in front of me.
I have seen your work on here and have been suitably impressed that you have what it takes to chase that ring!