is this the "free" motor??
Right now, the Chevy pistons mean NOTHING at all until you measure things to find out why they used them??? Could have been done cause that is what they had laying around and figured out a way to make them work.
All it'll take are a few measurements to figure out how "radical" the motor is...the only things I can think of to make a motor too much for street use is wild cam (which can be easily replaced) and wild head porting (sketchy ground here, depends on how much work was done such as porting or huge valves) and too high of a compression (this can be fixed with spacers under the cylinders or copper gaskets between the head and cylinders)
You are sweating this too much, unless everything is garbage inside of the motor from damage, you'll easily be able to trade for bone stock 2.0 parts if the motor is indeed "Trick"
If you get the motor within the next week and take it apart, I can meet you for lunch and I'll bring some of my stock 2.0 parts and we can do a comparison if you wish (crank, rods...)