If you look at the past OINP invitations in this link:
https://www.ontario.ca/page/oinp-express-entry-notifications-interest#section-1
The only time they drop the minimum CRS around 350 is when they invite people with a job offer in Ontario or the French Speaking PNP stream (for which you have to get CLB 7 in the french test TEF) otherwise if you only have IELTS and no job offer, the FSWP stream's minimum score is around 430.
So, without TEF, job offer or PhD/Masters streams, that's %99,9 improbable to get an OINP invitation with 350 CRS.
Sorry mate