It should be doable but there are things that can go wrong that would make it dicey. The Air France gate is not far from CBP and unless you get really unlucky it is a very quick process. The only thing I'm not sure on is the connecting passenger process as you'll need to clear US Customs in YUL. Now that I have NEXUS it literally takes about 3 minutes start to finish but during the wrong time the line can be pretty bad from what I've seen. Before I had Nexus I noticed people coming in from the opposite entry point which I assume are connecting passengers. These people seem to be zippered in with the current line but that kinda depends on the agent. The Delta JFK flight usually departs out of gate 89 which is as far away from security as you can get but still no more than a 5 minute walk.

Assuming an on time flight I would think you are looking at something like the following:
-Deplane and clear Canadian customs: 10-15 minutes (leaving 1:10)
-Collect luggage for transfer and drop off at transfer desk: 15 minutes based on what I have seen when checking bags (leaving :55)
-Clear US customs: 15 minutes (not worst case but probably medium, leaving :40)
-Clear security: 15 minutes (surprisingly slow sometimes given that the line is usually small, leaving :25 minutes)
-Walk to gate 89: 5 minutes leaving :20 minutes to spare and they don't normally board the JFK flight until about then.

Now, if anything goes wrong or there's some arcane process that I haven't seen between the transfer desk and US customs I think you'll be in trouble. If you had Nexus I think you would be fine. If it somehow drops below that time I definitely think you would be pushing it. That said, if you are one of the first ones off that AF flight AND your bags come out right away AND customs has no line AND security has no line (all possible) you could probably do it in 35 minutes or less.