buy a 2001-2004 H6 outback listed as needing head gaskets, put the engine in that. (a drop in)
drive it and be happy. rust free one can be had for $800 or so. (a couple years back I could have had one for $400)
then you will have time and sanity to work on the 2005
for the 2005. although I like the idea of a 426 hemi, a 440 wedge has less maint and easier to come by,
and then you can source out a 2005 legacy / legacy outback engine for it. (2005 is a really really weird year,...trick is finding a rear end wreck with one, they exist, just might take some time to find it).
what happened to the 2005 engine now? (if its just oil leaks,...do the head gasket job like EVERYONE else).