tune help

First things first.
- Do not assume initial timing is 'about' 20*, check it because that cam will need AT LEAST 20* if not more for BEST IDLE.
- Remove the carb. Turn up side down & check how much transfer slot is showing at idle. Any more than 0.040" [ 1mm ] is too much. It is likely to be MUCH more than 040 because you are not using the PCV, which would normally add some air; the blades are now opened further to compensate. Leave the PCV disconnected for now because it will NOT work with your low vacuum.
- with carb off, remove airhorn & check that float level is 7/16". Unlike brand H & clones you will not need gaskets if you are careful.
- If f/level is correct, you will need to drill a small hole in each secondary t/blade [ not the primary blades as most recommend ]. Start with a 3/32" hole. Refit carb & test again for idle etc. I suspect the 3/32" hole may need to be much larger, up to 9/64", but try in increments. Aim is for 040 - 020 & less is better of T/slot showing at hot idle. You get that by drilling the blades. Trial & error.
- if the f/level was incorrect, set it correctly & do the above test.
- Report back once this has been done.