Tenbrook asked me to post this here when I posed the question to him,
I am using your boo arrow build along (awesome by the way), but I have no "known spine" arrows to get a baseline, I am looking for 60-65# spine. Using 2#, how far would you guess the arrow should bend below the plain of the nails for that range? I'm thinking 1-1.5" but it's just a guess.
He is going to spine and measure an arrow for us and put his findings here.
Figured this might help someone.