This Dakka article should provide about as many answers as you can expect to find. The trouble with matching
40k to a real-world scale is that the
GW designers aren't even consistent, let alone realistic. Heads and hands are large, guns are huge, vehicles are squat and chunky while still being undersized...
Some vehicles can be made to fit reasonably seamlessly, but most you will find only match one dimension or another - the right footprint means the hatches and weapons are tiny, the right length means the hull is too skinny, etc. Airplanes are frequently the hardest of all, since most
40k flyers are less aerodynamic that your average cinderblock. Your best bet will likely be to look for larger scale kits of smaller aircraft - a 1:35 2-seater will likely render more useable parts than a 1:72 bomber or cargo plane.