Which OEM short block do you recommend?
The 10103AC870 is the current P/N for both a 2005-2007 Legacy GT and 2004-2006 Sti. That can be had for $2k.
I've also found the 10103AD020 P/N. That is OEM RA EJ257 for the RA2018/STi 2019-2020. It has forged crank, rods, but improved cast pistons. No idea what bearings. It can be had for $2200.
Otherwise I can get parts from someone getting rid of parts. Machined block bored to fit new Upgraded Cast pistons. King rod and main bearings, STi forged rods. I would buy a new 08-11' STi nitrided crank. Build it myself, I'm at $1550 that way.
The car had the heads redone 15k miles ago. Current original block already has ARP head studs, Killer B oil pick up, and new timing components along with Gates Kevlar timing belt. I can reuse all those parts. Like you said I would do the 11mm oil pump too.