The problem with casting a new intake is the small reed block. The block can only handle a 12mm carb, so you'll need a larger one. I had good luck making one of those 19mm dellorto pocketbike intakes fit to mine. I just had to expand the stud holes. I think I have pics somewhere... I have to find my flash drive.
put on a larger carb, port it (the ports are tiny just like most other stock bikes), make a custom exhaust with a larger header and an expansion chamber. I'm not sure if another bike has the same angle for the pipe. If you looked around, I'll bet you could find one close. I'm pretty sure puch kits will fit with a little modification.
I know the 2 in the 40/2 was the number of gears. I thought mine might be the only one in the states. I've never heard of anyone else having a 40/2. everyone else I've seen with an odyssey had the 40/1 version. I'm not sure if the 40 means anything really. Mine is 49cc for sure, so it can't be the cc.