Not sure, looks like a 350 car. https://chicago.craigslist.org/nwc/cto/d/arlington-heights-1971-buick-skylark-gs/7739320174.html
No underhood shots & looks like maybe an early '70 tach font w/flat lens & they should've added gauges along w/it. That said, maybe a lot of $ of a '71 350 but otherwise if the rest if the car checks out, that sure does look like a nice car!
