I’ve read this post on how to crossflash P5Kc motherboard with P5KR bios in order to get AHCI (remember you will lose DDR3 slots if you do this)
Since I have no floppies anymore, I’ve made an ISO with W98SE “DOS” in it, and the 703 rom P5KR file as long with AFUDOS 2.11
Hope this will be useful BUT REMEMBER!
BIOS flashing is potentially risky, if you do not encounter problems
using the current version of BIOS, it is recommended that you NOT flash the BIOS.
To flash the BIOS, do it with caution.
Inadequate BIOS flashing may result in system malfunction or motherboard DEATH
Here’s the ISO
on the road to your ass 