Go for a drive.
Watch the A/F meter at 500rpm steps. You'll see where the mains start to come in as the mixture will begin to richen up.
If you are rich below that point, look at the Idle air bleed/Idle feed restrictors.
Initial timing plays a big part in idle settings. Make sure you have plenty with an XS282s and a 273. More than 20 may be about right for that set up.