Hi Lureman,
This isn't uncharted territory. The three engine models mentioned will respond well to a 10 to 11mm Walbro or Zama carb. The insulator/manifold bore needs to match the throttle bore of the carb for the biggest improvement. Of the three the weedeater is the only one that may need a 9 or 10mm carb, because some of them have rather small ports. The Ryobi already has a 5/8" intake. The Homelites and Weedeater manifolds need to be bored out. It is usually necessary to install a external pulse hose to the crankcase for the carb pump on these. Do a RCU conversion forum search on carbs, there is a ton of posts on this.

Dave