Those gaskets are made for magnum motors. I had Detroit one piece one and his leaked immediately. The listing is Summit was B.S.
The magnum motors have a slightly different pan. The corners of the timing chain cover are a different contour. Some people have added metal blocks to there older pan/motors to make up for the difference. Try to Google it
Get and old fashioned cork end rail pan gasket set.
Before (notice gap showing at corner).... Then after years of leaking.