Xantia 1.8 wont start

[Maukka]

Car is a 1995 Xantia 1.8 16v petrol. manual transmission.

It has been sat some years, bought it for spares but shell turned out to be nearly rust free.
Have tried to get it running but damn thing refuses to go.
fuel system works, injectors fire that part is good.
Timing belt is intact and engine turns over fine
Have tried both original and known good coil pack from few years newer 1.8 16v.

Ecu was missing when i got it, got a used one that supposed to not have immobiliser stuff. From what i can tell it has never had one. Not even the keypad.
My other 95 doesnt have any either but being a 2.0 cant swap parts over to try.
Was missing the key and lock cylinder too, but i have installed the bottom plastic part on it. (wich starts the other 95 model no problem)

only missing part is the alternator. Could that prevent it from running?

Any advice on what to check for next? Dont want to spend more money on it before knowing the engine is good.

[xantia_v6]

Did you check that there is actual spark at the plugs? If there is then I would try with a little easy-start to check that the valve and ignition timing are correct.