Good news!  I successfully got SunOS 4.1.4 to boot in a qemu sparc emulation of an ss-10. I was told SunOS 4.1.4 would not boot under OpenProm but apparently they’ve made some improvements because it did.  It spewed a number of errors but none of them were show stoppers.  I haven’t installed it yet but this is the first time I’ve even got it to boot.  It’s been so long since I installed SunOS that it’s now mostly a human memory problem not a machine problem but I’ll get there.