Howdy, I'm not the expert, but from my reading your chrono results are somewhat meaningless without knowing the grain weight of the arrow(s) used. If you were using a 500gr arrow, I think those speeds are better than average. If you were shooting 700gr arrows your bows are awesome. If you were shooting 330 grain arrows your bows aren't living up to there potential.
There are several opinions on maximizing arrow speed from a given piece of wood, but they seem ( to me) to boil down to leaving just enough wood in the bow to avoid breaking. The member who posts here as 'badger' has done some amazing work along these lines. His conclusions are that the physical mass of the bow is one of the best indicators/ predictors of efficiency. That's efficiency in a an engineering sense, or in other words maximizing the return on the energy your muscles put into the bow as you draw it. See the chapter on the mass principle in TBB4, or check some of badger's posts.
The tips should be as thin as you can get them without there being much bend. Actual dimensions will depend on the density of the wood you're using.( For maximum arrow speed.) The last 6 inches or so can be surprisingly narrow.
Ron
