Starting a fresh rebuild

[vex]

I seem to have some trouble starting a fresh rebuild.

The seals are new, the apex seals are new, but the housings are used as are the side seals and corner seals. All springs have been replaced.

I have spark at the coils.
I have air without issue.
And I have fuel pressure and I hear the injectors firing (I know they're good because they were cleaned and flow tested).

By all means I should be getting at least an attempt to start. All I get is it cranking. Strong exhaust pulses can be heard so I don't think it's anything catastrophic. I would however like some sure fire ideas or ways to get this thing to start.
(I've already primed the oil system)