When you say "toothed", are you referring to weaving in the new floor to the old by staggering the butt joints back to factory ends? It sounds as if that is what you mean and are have trouble doing. It was common practice in older gymnasium floors to gap the floor boards periodically so the floor would not warp and buckle when the humidity levels would rise. Gym floors are typically maple and maple is a mover. How often gaps were intentionally left would depend on the size of the floor and the geographical location. I would bet if you waited till summertime, when humidity levels are highest in most areas ( except desert climates ), the old floor will expand a bit and they will not be as large or have as many gaps. This is common in older gyms without modern climate control systems. Older ones usually just had a huge furnace hung from the ceiling. Most had no AC unless it was added later. They just had rows of windows near the ceiling for ventilation. These conditions, along with the great expanse of maple flooring, required expansion gaps built into the floors and very large expansion spaces at the perimeter with large, plastic like cove mouldings that had vents in them to allow the space under the floor to vent as well.
All that being said, you should make every effort to weave the new flooring into the old and keep the existing expansion gaps. Increasing the humidity to normal levels may help with the install. You may want to contact the MFMA ( http://www.maplefloor.org/index.htm
) and discuss this with them. They have a technical questions dept.