It astonishes me this could keep coming up on a car forum, but more displacement does not mean a "bigger motor."Would using the TNGA platform give it the extra room for the bigger motor?
The FA24 is the same size block as an FA20, just bored out from a square 86mm to 94mm. What takes up additional space would be the turbocharger, intercooler, and any additional fluid capacity needed.
My understanding of the FA24 was that it was designed for a flat torque curve and regular fuel though, so I imagine they'd want to tune it a bit differently for the 86. That's if it's an FA24 at all and not a turbocharged FA20, given how many markets penalize that extra 400cc of displacement...