Yep, what Art said.
That caul design will put reflex in the tips for about the last 1/3 but you also end up with about 2" of deflex. I don't know how much that will vary the design that Art mentioned, but it is more challenging to tiller.
I like using the same basic layout that Art mentioned with a straight taper from handle width of 1 1/4" down to 1/2" at the tips. My next one may be even skinnier? I'm thinking the last 12" or so taking it down a bit more, dunno yet.
I think either way you will have a shooter Justin, just go with what feels right and step outside your comfort zone, but listen to Art he knows some stuff. Especially with working a set of billets.