Yep, if working from a set of plans it's typical to see a size for wheels. Typically it's the same for any commercial stock canopies. And often the plan suggests a brand and size of pilot.

If building a scale model that does not suggest a size for the pilot then it's....

Model Span in inches X 68 inches = height for a scale version of a 5ft 10inch pilot for a full model with arms and legs.
Real plane span in inches

If working with just the head and bust use the same scale factor for spans in inches X 9.5 inches. That's the height of my own head. Look in a mirror with a ruler along your head to check your own head.