Old crock pots with a mild degreaser and a couple hours of warm soaking will clean carburetors. I bought a large crock pot at the goodwill store for $5.00, and use Simple Green and water. If the customer wants it all one color, I will soda blast the out side for a uniform finish.
If you are eager to buy jets, go one size bigger then stock 283's used, at least it won't run lean while breaking it in. The carburetor doesn't know what intake or what engine its on, it's looking for air velocity. Your carburetor is calibrated for a 283, the 292 is not that far off from 283 and will work as it is.
