Depends a lot on your oil pan. There are 2 different front seal requirements on the pan gaskets. Problem is made worse when you try to use a later "correct" GM service replacement pan. GM started sending out the new "thick" gasket service oil pans for EVERYTHING regardless of original year of the application. A service GM produced '69 302 pan sold after the change in the mid 70's would leak badly with a '69 "correct" gasket. You would need the '75 and newer thick front seal pan gasket in that situation. Originally, GM would send a new style gasket along with the revised pans but that was a LONG time ago.
Try the thicker front seal pan gasket spec'd for a '75 drivers side dipstick engine.