[rescue] Sun Ultra AXe... SCSI RAID card?

[mrl]

I just purchased an Ultra AXe mobo + 300MHz proc + 256MB RAM. 
I want to put in a RAID card that will be supported by OpenBoot (so that
I can boot from an array), but I'm a little unsure of myself...

http://sunsolve.sun.com/handbook_pub/Devices/SCSI/SCSI_SRC_P.html
http://sunsolve.sun.com/handbook_pub/Devices/SCSI/SCSI_RAID.html

the above two cards on the only ones I can find on sun's web site, but
they're 64bit PCI. In addition, it doesn't mention the Ultra AXe (or
even the Ultra AXmp, which actually has 64bit PCI slots AFAICT).

I've heard before that 64bit PCI is usually backwards compatible with
32bit PCI, even though the 64bit PCI card is longer than the 32bit PCI
slot. Can anyone confirm that? 

If it is true, does it apply here? And will OpenBoot recognize the card?

Does OpenBoot have support for any non-Sun PCI SCSI RAID adaptors? All I
need is Ultra 160 or slower (I don't want to pay for U320, and even U160
may be overkill... I'm not sure what my drives are. hmm.). 

http://www.sun.com/io_technologies/ihvindex.html

has a listing of 3rd party controllers that sun says are supported by
solaris, but there are no RAID cards among them from what I can tell. 

Is my only change to get an external SCSI RAID box? I rather hope not,
because I already have a D1000. 
Ext boxes go for weird prices on eBay. There was an A1000 with no bids
at 150$ (no drives) a while back, but I've also seen em go for much more
than than (no drives).

If anyone has any other ideas, I'd love to here em.