1973 valiant 318 car stalls when compressor comes on

I have that same 2 brl. and intake on my 273. It came off a 73 valiant with factory p/s and a/c. it never had a throttle kicker on it. If the 318 was tuned properly it made enough horse power at curb idle that additional load from the compressor was hardly noticed. Low timing along with todays pizz poor fuel? a/f mix wrong due to a vacuum leak? Root question... How well does it run without a/c engaged?