Lack of photographic evidence certainly does not mean there was no bridge.
I actually worked at 93 Claireville Drive for a time, which is the building just north of the new Mosque that is north of Finch. The mosque was built right where an old house used to be which you can see in the aerial photos. You can actually still see a remnant of the old Indian Line just before it would have crossed the Humber at the 427/Finch exit - as a wide flat path of grass visible when you travel South on 427 just to the left of the exit to Finch Avenue.
They continued to widen the 427 up to Finch Avenue and put in the Finch bridge and extension. Initially they left Morningstar Drive open with a stop sign in the middle of the 427 as you turned left heading north. They planned to close off Morningstar, but my understanding at the time was that due to a lot of taxi drivers who lived in the area, they left it open to allow easier access for them. (I'm not sure how true that is but that is what we were told.) They put traffic lights there as it was becoming very dangerous to cross the 427 to get onto Morningstar. At some point when they built the 409, many of you may recall that there was no ramp from southbound 427 to eastbound 409, but traffic lights there to turn left across northbound 427 then down a ramp to the 409.
For a short period of time during this construction there was also an access road that believe it or not ran off the southbound 427 just south of the railway tracks that went steeply down the embankment to Goreway Drive, just opposite was is now called Zahavy Way. It was a pretty awesome shortcut and very steep. It did not last long.
I swear your site is the one that I mentioned here a few weeks (months?) ago about lost and hidden road ROW's. I remember viewing a site in the late 90's, early 2000's that covered humberline as well as a road closer to the airport in the industrial park...