I can prepare any of the following publicly available Super Nova BIOS for you:

sknsa1.u10
sknse1.u10
sknsj1.u10
sknsk1.u10
sknsu1.u10
supernova_modbios.u10 (I have used this to get region free on a Japan board)

EPROM is custom burned to your order. Let me know in order notes which chip you need.