The code you see, can come in "pairs" being that the engine uses two sensors of similar construct - and location of them being on their respective shafts, the "!7" code is an Exhaust alignment error code.
The other of the Pair is P0016 or the "16" code - being it's on Bank 0 - and means Intake side - alignment error.
So, this brings up what others beat me up on before. I'm still here though, so you know, I have no "PhD" for Automotive degrees, just common sense - go figure that...
- There are so many variables and whatnots, so there is no real way to cover all the bases these things need to have done so mostly what my approach here is, during the assembly - what can go wrong during the teardown that was not addressed before you got it, and you may never know what problems there truly was with this machine - so we can only guess and speculate - which makes this dangerous grounds.
Ok, before, when you found the motor in "pieces" and took over the mess. You had to put it back together - nice work. They may have had to tear down the motor for that code. But as to what that code was caused by, they (may) know, we don't (can only guess) - neither do you - so knowing the History is out of this equation. No History? Then none can't help us - for it could tell us but speculation is only what's left.
So using the old belt, no - start over with fresh.
Also remember - to release all the oil out of the upper cam advance units on the Harmonic balancer side when you re-set and redo the advance timing - these cam units need to be completely seated and empty when the belt is installed - the units hold oil to handle advance - so if issues came up - solenoids, as well as the oil changers (or chargers - chambers?) - can offer some insight into why the failure. IF debris is in one of them (as in clumped dirt or shavings in the housing), debris blockage in the solenoid, or solenoid is weak or they can't drain - this would change the RATE of oil filling and emptying the chamber, making the timing advance look "faster" or "slower" than it really should be - which is partially the reason why these codes are a pairing - being the different banks - all things being equal, one of the units is (
READ:might) not matching fill rates compared to the other - so it feels there is a mis-match but can't tell you why.
- To remove other doubts, including the sensors themselves, did you swap or could you swap sensor locations?
- Then the code - if it followed to "16" - then the issue would certainly be the sensor.
- But then the "17" if it stayed with the "bank" - then the solution is in the machine - not in the sensor.
- The sensor is keyed - so you might not be able to unless you have a spare motor in which to swap that sensor - so that's out of the question. Things are not as cheap in monetary as they once were - doesn't not always reflect this in quality.
Other Factors that can make the shafts seem to not sync right, is the cam teeth as well as the journals - did you have a chance to see in the engine in operation before you put the covers on? The issue of warping in one of the cams - being that 17 suspects the Exhaust side - the lobbing" might provide the clue you simply have to replace that cam - but to know that, you'd have to do a runout on both and find the tolerances.
Cam teeth use the belt so to use the old belt and this code, may be the belt because of poor quality control - we don't know. Best to try using a known good new one to remove that doubt.
Cylinder Head - true? Any warp? Gasket ok?
Any Spark Plugs laying around the teardown left behind? Can you inspect them?
The Crankshaft - the tooth gear - how is it's condition? Might need to verify it's in good condition. It uses guides on both sides of the axis, so they keep the belt "centered" along with the Tensioner - but that tensioner also takes a big chance on the alignment of the belts path also being true and not inducing a wobble nor the Water pump dragging this mess down because it's near the end of it's life and the bearing has headed south - the rest of the assembly has not left town yet. (
So you know, the Water pump is not on the same shaft, but uses the Serpentine to turn - but the Tensioner is near and by that Water pump assembly internal to the Timing Belt cover - the reason this comes up is due to a vibration or wobble on the shaft that can cause problems and induce a leak in the inside of the housing - it's a mess) 
