If you can adjust your fuel pressure higher for now, it really does make a difference in your AFR's.
I set mine to 38 psi @ idle vacuum line disconnected, & ran crazy lean like 15 to 1 I then adjusted to 55-60 psi vacuum line disconnected & my AFR's went to 10.8 to 1.
On a side note pertaining to your flow numbers, my friend that works on all kinds of nice 4 valve cylinder heads & others, sorta thinks your exhaust flow numbers seem correct but your intake cfm seem too high. Not saying you are wrong & also my friend has not flow tested a Trailblazer head yet,but he has flow tested modded Toyota turbo Supra heads & those are nice flowing heads BTW.
It will be interesting to see your flow chart when you post it.
Also it will be interesting on how much more power your engine will make over our old style L6's
