So bought an ILF bow. I have the 21” slither riser on order with the long October mountain reaper limbs (which I’ve already received in the mail. My questions are 1. My total bow length should be 66” so my string length should be 62” right? And 2. 40# long limbs with 21” riser. I know that the poundage is less with longer riser but with long draw it increases the draw poundage. That being said. What spine for a 32” arrow black eagle brand would you recommend?