The only way I've been successful at patching an oil pan with rust holes is to replace the entire bottom of the pan. Cut it back to solid metal and fabricate a patch that eliminates any possibility of further leaks. You're dealing with the bottom of a cone-shaped rust pit- - - -as soon as you start welding in the area of a leak, it will blow out to several times the size of the leaky spot. Either cut out and replace the entire rusty area, or find another oil pan. 1954 and early 55 pans will be the only option. They have straight pan rails- - - -in midyear 55, Chevy put an offset in the passenger's side of the block below the distributor to clear a bigger oil pump, and modified the shape of the pan to match. A 216 pan with the troughs and spray tubes removed will bolt onto the early full pressure block- - - -not sure about the sump shape or pump pickup being the same.
Jerry
