I'm still using my sf4008 and I have 6.3.001. Maybe it would be possible to upload somewhere?!
But main problem is, even if you find 5.4.016, you don't have feeds / plugins. For 6.3.001 I did build feeds too and installed few plugins manually.
It's not too diffcult to build image, it just takes time, instructions are in github. (Currenty there is 5.1 for oe-alliance, I did git checkout 5.2)
I mainly use only Windows and installed required Ubuntu to virtualbox.