RE: Stihl 65cc
It would do well on a D7. The exhaust is on the correct side. Making a scale exhaust pipe would be no big deal. I would probably leave the magneto. The flywheel is relatively tiny. The weird 11mm prop hub thread is the only possible issue. I re-threaded mine to 10mm. The straight non tapered crank works fine. The prop hub was easier to make accurate because of that.