Seeing as they were made December 1975, they are regular 85c electrolytics, and pretty much any modern cap will be superior to them from a ripple current and ESR point, and will run cooler as well. Not that the electrolyte boiled but that the rubber top bung has perished, allowing the borax electrolyte to bubble out and make that crust.
With the wire to them being single strand 0.5mm equipment wire ripple current rating was not something to concern as any modern part ( aside from that from some mystery Aliexcess supplier where they inflate all the specs by some massive amount, and make it out of recycled scrap) will perform just as good as the originals did when new.