Airfoil suggestion.
The S6063 with a slight reflex in the trailing edge of the wind tunnel test model has the lowest drag coefficient of any airfoil that I have seen reliable test data for. It is similar to the MH33 which is used on pylon racers. It is only about 7% thick so it would require special consideration of the wing spar design and torsional rigidity of the sweptback wing structure. The S6063 has a low drag range from a coefficient of lift of zero to 0.4 and stalls at a lift coefficient of about 0.8. This airfoil will be very fast but, the practicality of its landing and takeoff speeds will depend on the wing loading you design and build to and possible use of flaps.