It's subtly hinted that people can PM for the files...
It's copyrighted material, you know the drill. I have top loading bios files as well.
And for best compatibility I do recommend the JPN bios, yes.
My modified BIOSes have no SYSTEM checking (doesn't matter which regional setting your console is at) and no disc region checking (It also aways play it's own internal SEGA logo, disregarding the one that is on the disc.)