I got SF64. Originally it was getting as far as just past the 3DS loading screen, then crashing with "An error has occurred, hold down the power button, etc" I realized the problem was that I had minimum kernel version set in the .rsf where the original exheader (0x39C) had those bytes filled, presumably it wasn't something that was checked until later on and breaks compatibility with earlier games if you set it?
I've got a link to the python script I've put together to make (hopefully) working .rsfs, worked for SSB and Star Fox so should work for anything else.
https://www.dropbox.com/s/pks0oh8cb8c5olm/rsfgen.zip?dl=0
Optionally can patch the minimum firmware requirement for a game, if you're on 4.5 CFW, though obviously that only works to an extend and any games that use 7.x crypto or other features exclusive to higher firmwares still won't work. Also includes .exe versions of the scripts, if you get errors using the .py files, and a quick region patcher just because I forgot to take it out of the folder when zipping it and can't be bothered to reupload.
No promises about this having any guarantee of working, it's real lazy, bad python and method, and having almost never used python before I was mostly learning as I went along.