I'm sure it pulls timing out left and right because those are fragile engines. Not as bad as the 2.5's, but still not ideal.
I'd pull a plug or two, I recommend either cyl 3 or 4 or both on the passenger side, and look at the plugs or the piston surface if you have a borescope.
Also, yank the oil feed line at the turbo and see if the inline filter has been removed or not. The 04-07 WRX/STi had inline filters (as did the STi AVCS aka variable intake cam system) that were prone to getting clogged with shit and killing the turbo and sometimes the engine, TSBs all recommended that they be removed ASAP. If she blows any oil upon startup or under boost, yes it's the turbo but the engine's probably fucked as well if it's been driven any length of time like that. All of this is easily verifiable by searching NASIOC.