Easiest solution is to fill in with brass and a torch and then file and sand back down to correct dimension.

If you want steel instead of brass then the same "filling" can be done with a TIG welder and the correct filler metal. ER70S-6 is the common carbon steel filler metal. 309 is a stainless filler metal that is known for its ability to bond to dissimilar metals, so it is also an option. The amperage required would be low enough and the brazed joints are far enough away that melting the brass at the chainstays/seatstays would probably not be an issue. Then it would need to be filed down and sanded like the brass.

Most costly option is to have both dropouts replaced entirely by a framebuilder. If you'd like more than one eyelet or any other features it might be worth making this investment.