If you boot the VIOS partition and "pretend" that you are going to install does it display the disks? In other words, are you sure you have specified the correct slot (T10, T12, T14, C6, ??). If you cant see the slots to install on them, then they wont boot either.
If the disks can be seen, but don't boot this means that the firmware does not see the disk as bootable. Generally, the easiest way to resolve this is to boot in maintenance mode and run bosboot again.
Note the kernels for POWER and POWER+ are different, but once above TL4 for AIX 5.3 your kernel should support both. VIOS 1.3.0.0 is TL04 I believe. I have Fixpack 81 installed (VIOS 1.3.0.1).
$ ioslevel
1.3.0.1-FP-8.1
$ oem_setup_env
# oslevel -r
5300-05
I would consider updating my VIOS (1.4 is also available) to at least 1.3.0.1