I thought the METS plan might have been dead (or on life support) by the mid 70s. Isn't Yellowhead Trail a 'Plan B' of METS? There probably wouldn't have been the need for the current Yellowhead Trail alignment had it followed the MacKinnon Ravine, James McDonald Bridge, etc.
Assuming Hwy 2 still follows its current alignment via Whitemud Drive, taking advantage of the 91 St ROW to the south might have been better than Gateway Blvd/Calgary Trail.
IIRC, METS had a trident interchange at the south end where 91 St, Calgary Trail, and 111 St would converge.