Just from the looks of it, it looks like a stock 86/87 turbo.
Is there a nipple on the inlet bell that either has a rubber hose attached to it and run down to the passengers side valve cover, or does it have a rubber plug clamped over it? With a Garrett turbine housing and that factory inlet bell, I would say there's a 95% chance it is stock. I base this off of the fact that almost every TA-49 turbo that has been produced within the past 8-10 years has come with a new billet aluminum inlet bell. Also, it doesn't look like the downpipe elbow has ever been off of that turbo. Another sign of a stocker. All TA series turbos for 86-87s & TTAs, use the factory 2 bolt inlet bell compressor cover, which says Garrett, M10, and .60 A/R on the compressor cover. The only real way to verify 100% would be to take inducer and exducer measurements of the compressor wheel and the turbine wheel and call either PTE or Limit with your info. To my knowledge, no one has ever re-casted the factory compressor cover, they all just used the stock covers that Garrett made and machined them for the larger compressor wheel.
Hope some of this helps a little.
Patrick