Experienced Mechanic needs another opinion

[cypress TX 72]

I have a 350 SB that will not start....
I have fuel getting to the carb, plugs are moist but not flooded.
I have fire to the plugs.
When turning the motor over, it wants to start... but just won't.
I changed the coil in the HEI and tried again (thinking I wasn't getting enough spark)-- still no dice...
So I re-timed it by hand, TDC and re-aligned the rotor in the HEI..Just to make sure.
Still no dice...
The only other thing I can think is the modulator in the HEI is bad, or that the motor has jumped time.
This motor is fresh, it has about 4 hours on it, and the HEI is brand spanking new.
Please Help me out with some ideas.