Where is the timing set and what did you do to adjust the carb?
Generally make certain "everything" is in good shape, good plug wires and cap, plugs, do a compression / leak down and make sure the engine in good shape. Any evidence of leaking valve seals? Oil "puff" on startup?
Make sure float level on carb is not "high" and is dripping / dribbling/ "pullover" gas into throats. You can see by LOOKING at idle, down into the throats
Go look up some of the 74 specs. Set timing as retarded as it will run, TDC and make sure YOU DO NOT have a performance curve in the dist. Maybe just go buy a stock junkyard dist and get it "up to spec"
NO vacuum advance at idle, again, you want RETARDED and SSSSSLLLLLLLllllllooooowwww advance curve
Make sure it has a "hot" Tstat. Factory are 190-195-ish don't run a 180 and GET IT CLEAR UP TO TEMP before testing
Carb. Set idle "a bit" high and peak the idle mixture screws with a vacuum gauge, then "bump" them to the lean side (CW) just a tiny bit
