your body shell looks like a G11 that was diesel or was a turbocharged 2 door car, your engine looks like a CB37 from a G100. Does the picture of plugs on the air cleaner show a twin electrode plug?
I see the fresh air injector reed valve here, does it have the EGR unit on the other side of the engine? does the carburettor have hot water pipes on top for the thermal choke assembly?
speaking of the fresh air reed, make sure that the reed is sealed in one direction (should blow towards exhaust but not back) - if not then exhaust gases will be shooting into the air cleaner box.
The reed's job was to add fresh oxygen into the catalytic converter to make sure it remained super hot.