generaly you don't need to adjust your stock carb. there should have been a plug covering the low speed mixture screw. if it is running improperley you should rebuild it.
as far as the weber. i run them cause they are simpler and easier to work on. there is a C.A.R.B. aproved one you can get. make sure it has the tag on it.
have you spent any time with a shop manuel and tested the various functions on the stocker? i have found that the AAP valve tends to go out a lot. so does the idle jet sylinoid. how it the choke operation? the AAP valve was about 35 bucks from toyota 5 years ago.
