Well....... You got me thinking about that and I was going to post a reply to your message, but I'll just port it here. The carbs on these are little, like 24/64". That's because much of the air flows through the air valve, not the carb. But the 28/64" carbs are not that much bigger, and I was just contemplating giving it a try on a ported 40cc one I've been playing with. So I agree it might be worth the experiment. I have some carbs I can swap the shafts on.
Chris,
Let me know if you try it and what the results are. I'd prefer the venturis be the same, too, but considering the new Ryobi carb was $65 last time I looked, it's worth a try on a $13 replacement. I'll probably try it at some point, too.
David