I have put the Scalextric 1970 Mustang together with a 3D chassis as a sidewinder. The 70 Camaro on the 3D chassis as a sidewinder is about 3 mm wider at the real wheels than the Mustang fenders. The main problem is the sidewinder gear hub and slot.it wheel are too wide for the Mustang fenders.
Both cars could be assembled as inline which would allow the Camaro to run with tires well within the fenders and equal to the Mustang inline. Tests completed showed that the inline pod gives ability to set rear track width the same on Mustangs and Camaros. Can also use hubless wheels to get as close to the chassis as possible.
The inline pod will require cutting the bottom of the cockpit off to clear the motor.
I am going to stop testing here until we decide if this will be a 2019 series.