LT230quadsport

my son and I are restoring an 1985 LT230.rebiult entire carb new everything in it Timing is set dead nuts after reboring cylinder and replacing piston and rings. Engine is hard starting and when does start engine will only run with choke on idle revs up pops through carb and goes down. when you crack throttle enginge backfires through exhaust and carb. any Ideas would be great thanks