The Walbro wt-499 is NOT an alcohol carb. Walbro does not make Alky carbs. The WT499 is a gas carb with bigger than normal jets in it. So it flows enough fuel to work fine with Alky.
The Walbro master book has everything but jet size in it . So you can't just look for a bigger carb with big jets in it. About all you can do is find a carb that fits right and pop the welch plugs and enlarge the jets. You need to make the jets 2x the sq" size, not 2x the dia. Sort of hit and miss.
With the Ryobi having a factory redline of 7500 RPM the WT499 will pass enough air. Of course if you ignor the red line and twist it up to 8500 then the WT 499 isn't enough.
Its all part of the fun of converting engines