You should not have to change carbs. As for the design it is an excellent replacement (the differences in these saws are generally piston and cylinder, everything else is generally the same). As for a 'clean-swap' there may be some things you'd want to do. There has been a problem with some of the units and air leaks (you could discover this the hard way and be out the money you paid --i.e. install the unit without a pressure vac test and discover it through an air leak that kills the engine).
Some of the members have recommended that the unit be disassembled and resealed with a proper liquid gasket material (i.e. dirko, yamabond etc. that is resistant to oil and gas). If done correctly you can save yourself the trouble of discovering an air leak too late. Otherwise there is also a long range recommendation that you replace the chinese rings with a good pair of Caber rings. This should provide some insurance for you against "ring-breakage" and lengthen the life of the unit.
If I was to buy another one of these units today -- this would be my strategy. The ones I have purchased and installed, thus far have worked very well. Happy Sawing!