As to the front mount there should also be a sheet metal pan/cup which fits over the assembly as an oil deflector. I would think that if the square holes are gone I would try to find another metal assembly. Try Carters or some such place. Most likely would be used. When I assembled the mount I also put gasket goo around the holes in the oil shield in case oil leaked down from the timing cover. This helps keep the oil out which will find its way via a bolt.

1949 Chevy 1/2-Ton
"Sedgewick"
In the Gallery
1989 Caprice