What size pilot jet have you fitted, and what is the float height? Both have to be right to get correct fuelling at tickover throttle setting are are the first suspects if you can get it to tick over with the choke closed.
1. With higher compression you usually retard the ign (make it fire nearer TDC)
2. Main jet has no fuction at tickover. Do a web search for Amal tuning hints and you will get the info you need, but you start by running the bike flat out and doing a plug chop to get the main jet right, then work your way down through the needle jet, choke cutaway, pilot jet and the the air bleed screw.
3. Err – might be too much, the larger a carb the lower the inlet tract velocity at low revs (like tickover) so the poorer the starting and slow running performance, especially noticable when opening the throttle fast from a tickover.