Not mine... No engine pics - but based on the photos and the TA cam description it is a 350. Hope the link works... https://seattle.craigslist.org/see/cto/d/port-angeles-1973-buick-century-luxus/7709335317.html
Advertised on Seattle Craigslist, located in Victoria BC and that's on Vancouver Island. I always find it a bit strange that the capital of the province of BC is located on an island..... Anyway, here's a screenshot of the listing: There is an engine photo listed: