Well, you could do a lot worse than having a motor with similar specs to a Maico 490. I believe using a standard 490 piston is a common practice in 465 motor builds, which gets you purty close the Maico 490 B/S ratio.
EG loves old school 2 strokes. When I talked to him last year he was getting ready to join Millennium Technologies last November and his prices were getting ready to go up. Still, he can build a 465 to do just about anything you want from the motor.