We fly 1cc stunt at all the Knights of the Round Circle contests.  Single .061 c.i. or twins up to .101 c.i. power is the only limitation.  Planes usually run from 150 sq.in. for the Baby Clown and Baby Flite Streak up to 235 sq.in. for the Baby Magician and Pathfinder.

There is an extra award called the Leprechaun trophy for the best scoring model that is a replica of an Old Time or Classic model.  The Pinto, Flite Streak, Baby Clown and Baby Magicial all are kits that qualify for this.  There have also been others such as Tim Meek's Replica Midwest Mustang, Don Butman's gaggle of models and Lee Strickland's Little Ringmaster.

We are still debating how to regulate the use of electrics so that they are equivalent.  Currently (sorry, pun) the thinking is to put a limit on Watt-Hour capacity of the battery, and let the designer choose how to use it.  That would cover multi-motor and single motor models with the same guideline.  My current estimate is 16 watt-hours.  That would be a  2100mAh x 2s, 1400mAh x 3s or 1100 x 4s LiPo pack.