the cios38 installer USES the IOS of your choice (which must be patched, people usually use IOS36 after using the trucha bug restorer) to install the cios to slot 249, by default it makes a backup of itself to IOS250.
If you run the installer, it will probably error out if you haven't deleted the IOS249 stub (never tried this myself, but since your trying to install rev 14 over rev 30000+ (the stub), it should fail, as you cannot install an older rev without first deleting the newer one)
Yeah that's exactly what happened during the cIOS38rev14 install. I got an error installing after selecting IOS249. So instead I selected IOS250 according to a guide I read. It installed successfully. Only later did I find out how to remove the IOS249 by using wad manager to uninstall it. I tried to use AnyTitleRemover previously to remove the IOS249 stub, but it was not listed.