Fortunately, modern .30-30 cases can be converted to .30 Remington fairly easily if you have a metal working lathe. It doesn't even have to be an elaborate one.
All you have to do is turn the rim to the proper diameter.
You MAY have to recut the extractor groove, but apparently that's not always necessary.
"The gift which I am sending you is called a dog, and is in fact the most precious and valuable possession of mankind" -Theodorus Gaza
Baby Jesus cries when the fat redneck doesn't have military-grade firepower.