Your desire to make “fast” wings for racing involves a lot more than a laminar flow airfoil. The laminar flow (six series) airfoils do in fact have exceptional low drag coefficients at relatively low angles of attack. However at larger angles, they are not any better (and sometimes worse) than more conventional shapes. Such varied airplanes as the P-51 and the low wing piper aircraft use a laminar flow airfoil. In both cases low drag in cruise is an important design parameter, the P-51 as a long range bomber escort, and the Piper as a traveling machine. For flat out straight away speed where the angle of attack can be kept in the drag “bucket” they can be a good choice. However for something like pylon racing, any gain in the straight away will likely be lost in the turns where operation at high angles increases drag significantly.

Radio control models are constantly turning to keep the aircraft in the confines of the airfield with little time spent in straight flight. For such a flight profile, there is little to be gained with the laminar flow airfoils, especially since a slightly cambered airfoil with the maximum thickness a little farther forward usually gives better overall performance in turning flight. Since you mentioned giant scale, you can’t go far wrong using the scale airfoil. The AT-6 uses a slightly cambered airfoil that should work as good as any for a model.

To go fast (assuming the engine size is a given) keeping the weight as low as practical will be more effective than almost anything else you can do. Light wing loading and high power loading are the two most important ingredients for speed. Some areas of possible drag reduction include engine cowling, wing/fuselage interference, landing gear, etc. You must evaluate the drag reduction vs the added weight. These modifications may be limited in a scale model.

As to tail surfaces, it’s hard to beat the conventional slab design. It’s simple light and pretty low drag. That being said, if you use an airfoil section for the tail surfaces, a modified laminar flow with the maximum thickness at about 50% makes some sense as the tail surfaces operate at quit low angles of attack. I say modified because the “cusp” trailing edge typical of the laminar flow series airfoils is not particularly suitable for control surfaces. Since the drag of the tail surfaces is a small part of the airplanes overall drag, don’t expect too much improvement.