Saadaoui, the main instigator, planned to smuggle AK-47 assault rifles, handguns, and ammunition into the UK, with police describing it as potentially Britain's deadliest terrorist incident.
The plot was thwarted by an undercover operative, referred to as Farouk, who gained the trust of Saadaoui and monitored his activities.
The defendants conducted reconnaissance in Dover for weapon smuggling and surveyed Jewish nurseries, schools, and synagogues in north Manchester.
Saadaoui's brother, Bilel Saadaoui, was also found guilty of failing to disclose information about the planned attack, with all three awaiting sentencing on 13 February.