"...If the ‘mystery’ Canadian ZL-1 came from Detroit it virtually had to be a Merollis car..."
It'd be worth running these Merollis Vins by George at GM Canada Vintage Services!.
Being the car was somehow directed to Nurse Motors by GM Head Office in a non-standard way it's possible the normal procedures weren't followed...but if they were, the Vin should be included on GM Canada microfilm and something George can access!?
And I'm not suggesting George search his records for anything other than specific Vins given and it may cost the fee for each and every one checked so best to start w/ the most probable and go from there?.
On the missing ZL1 cars Vins being registered in Ontario, YES there's something fishy going on and it wouldn't be surprising if they're registered in the same names as other 'interesting' Vins/cars and suspected 'air cars' we've looked at here in past threads?.
~ Pete