The carburetor repair should be OK Mark, provided you got it square, and the screw doesn't come loose (I'd have used loctite on the screw, and probably let it sit around for a few days before exposing it to petrol - loctite works by corroding the metals of the two parts so they are chemically bonded, but it takes time to work unless you clean both parts extremely effectively with industrial solvents).
At 14.8 kg I think that 106 cc 2 stroke weighs as much as a Briggs of the same output, so it isn't a lightweight engine. However the base engine is probably quite a bit more durable than an aluminium-bore Briggs too. Depending on whether they used another Mikuni carburetor and a complicated off-beat linkage like on the Suzuki M120 engine, it might have been quite a good choice for a contractor. However I think for most contractors, durability is less of an issue than reliability and low service costs. Fuel consumption also matters, and I doubt it performed very well in that regard.
