27 mS even with a small injector is a TON of fuel.
To clarify, there is BPW and HR BPW. One is High Resolution BPW. I don't remember off the top of my head which is which, but one of them is half of the other on bank to bank systems only. If you have a sequential system they are the same. They may also be the same value on bank to bank Buick systems since they only fire once per combustion cycle even on a bank to bank.
Whichever of the two values is the smaller is the total pulsewidth for the cycle. So, if you are idling at 4.1 mS and trying to stuff 6 times that amount of fuel in the engine, I think this is probably a big issue in your starting problem. Without trying to sound too critical, you are lucky you haven't started a fire in your exhaust system. I did that recently on my own motor on the dyno. The heater element in the O2 sensor lit the unburned fuel in the pipe and spit big gnarly flames out the header.
Drop your cranking fuel to 5 or 6 mS at operating temp, taper the whole curve accordingly, and see what happens. I predict that things will work well for you.... let us know.
he's right, but don't expect to see any readings from the O2 sensor during cranking. There will never be enough airflow across the sensor.