As someone who has been in and out of karting several times since the 90’s I can tell you this.
Local is easy, run whatever everyone else is running if you want to run with lots of competition. Beyond that, its a mess, especially if you are trying to run several different series, want to be competitive, and you have a tiny budget. Any two of those are ok, but you can’t get all three.
I’ve run Briggs flatheads on Alcohol, 125cc Shifters, TAG’s, and now LO206.