G70+ is a pretty wide category that encompasses everything from Showroom Stock cars all the way to something like an IMSA GT car from the late 70s. The trick is that you are supposed to prepare a car to a set of rules from a specific race series from the 1973 - 1989 time period. In my case I would be choosing the SCCA Escort Endurance series rules from 1989 to prep the car to, so it should remain largely stock by that set of rules. Putting it together as a Saleen, taking a 50 lb. weight penalty compared to a regular 5.0L, allows me to run 5-lug 4-wheel disc brakes, and then I should also be able to get away with the 65mm throttle body, 1.72 rockers, 3.27 or 3.55 gears, and FMS shorty headers, since those were all pieces that came on the late 80s Saleen production cars.
If I do make it out for G70+, Mt. Tremblant would definitely be on my list at some point. I've crewed up there a few times in the old Firehawk series, but never have driven on it. Can't be any tougher than Mosport, right? :P