[lunatic]

if you can get Linux installed then the hardware should work in general.
Older Solaris releases might be picky about disks. A 4/40 is an IPC, right? So it should boot Solaris 7. Boot Solaris 7 and use format to create a disklabel and partition the card the way you want. Then reboot and boot Solaris 2.4 or SunOS. Just install the OS without repartitioning. Even SunOS 4 can use a disklabel created by a more modern Solaris just fine.
Older releases might not be able to use file systems larger than 2GB. That is certainly true for SunOS 4. I think Solaris 2.4 could use larger filesystems. One limitation that generally holds for all 32bit SPARCs is that the boot partition (so the root partition essentially) must be within the first 2GB and not be larger than 2GB.