Nothing wrong with a little copy here and there. I just did two 13.5 risers. I have to look to be sure but the bolt holes are 3 5/16s from the end. That build Jess talks about is on POA and he used a machined insert and routed the riser They called them donkey plates Feral Donkey over there machined a few out. I have a set somewhere. If I can find them you are welcomed to them.