Frank not sure what your experience is,but wih my 67, stock 225 with a clifford full length header and a 1 bbl it didnt work no matter what jet I used.Even a 61 jet in the 1920 did not work.Idle was great,stinky but ran smooth,as soon as I would breathe on the throttle it would go lean and surge.I would recommend some kind of tune able 2 bbl or 4 bbl.Just a jet change wont cut it.
With 1 bbl 1920's I converted several Dusters from the 1945 carb to the 1920. I could never seem to get the 1945's to run right. NOT all 1920 are good (or even ok) as I have thrown a BUNCH in the scrap bin over the years.
I used to super six ALL my slants (except the race engines) but have found that some cars like the 1bbl much better.
Did you just change the jets or did you mess with the air bleeds and such? I have had some real problems with the smog versions and plugged passages.
Frank