Good Q but sadly no clear answer
Yes this has been explored before.
There is unfortunately no best mechanic in Klang valley (that I know of at least) hence part of the reason why rotary has such a bad reputation.
However, IMO Ah Choi is still the best for general repairs to rotary cars. However, rebuilding I am unsure given (perhaps unsubstantiated & unscientific) claims from other RE owners.
Personally I didn't have faith in anyone rebuilding my engine locally after researching it when I encountered an o-ring problem with my RE so i did it myself with some $$$ investing in rotary specific tools. However by training I have mechanical engineering background.
With the right tools, good guidance, some handiwork you can rebuild your own engine too - but you must be skillful with your hands and have loads of patience and care!
REs are more reliant on correct tolerances for wear and clearances of rotating and sealing surfaces over and above piston engines! This translates into - you cut corners or try to save money by reusing "questionable" parts in your rebuild and you're engine will never run well or last. This may explain why the average rebuild lasts only 6-12 months. All parts during rebuild need to be measured as per Mazda specifications you can't just do the usual eye test that "mechanics" are familiar with - it takes more skill and care than that by a mile.
You can find out more in the links provided earlier by sakuraguy.
Happy hunting for your Rotary dream!