74 Scamp slant, auto, "better" carb?

The 74 Scamp will soon face cleaning up the mechanicals, brakes, water pump, maybe filter/ fluid change AND DO SOMETHING with the carb

Minimum..........clean and kit, but these 74's have a habit of being pretty lean, some of the worst smog years

What is a viable "different carb" that is closest to "bolt on" IE does not require vast reworking of throttle and kick down?

I prefer not to spend a "tremendous" amount of money on this as I'm not sure yet where this is going....