I didn't. I cut the plate under the needles (the original guide, that helps adjust the needles on weed whacker) as it interfered with throttle linkage. This was the only mod to the carburetor.
For adjusting needles while engine is running I made a simple tool: U-bent 7/32 aluminum tube, that the end I pressed to the mixture adjusting screws to shape the 'grabbing' part. It was not a rocket science

See pictures below of the tool and the engine. My home made test stand works OK as long as someone holds it from the back. I also show throttle linkage - easy and clean solution. Details of modified muffler and finally the magneto strike.

Enjoy
RysiuM