I printed my final version with no supports, PLA, 90% infill, 3 walls and it seems strong enough. i got away with no supports but you might want them

motor mount holes are 25x19mm apart

cut slits in the foam for bottom of mount to press into.

Drill or some other other way (I used a dremel with a grinder bit) to widen shaft hole on stock motor mount at the nose to give the motor a bit more clearance

No

Doesn't Matter

90