wrong wheel cylinder

Ok....

Raybestos Part # 37286 fits 73-76 with 10" brakes
1 1/8" bore
3/8 - 24 inlet size


Raybestos Part # 36050 fits 68-69 with 10" brakes
1 1/8" bore
7/16 - 20 inlet size

The illustration for the #36050 has the football shape like in your pics above.