Bon Ami isn't abrasive----------the old adds used to towt "never a scratch"

Any way-BA has over the years been used on varius lapping in opts-----you sprinkle it above the carb while you rev up the motor-rum, spr BA, rum, spr BA, Rum, Spr BA-----------do it over one primary port at a time, going back and forth as it will go into 4 cylinders according to your intake manifold design-alternating with sprinkle, rev, sprinkle rev sprinkle rev---------a few times and switch ventruies-
This has been used over the years on many industrial engines, race engines, aircraft engines,etc to lap in rings that weren't seated properly---------and today it seems that more and more rebuild projects are resulting like yours probably from faulty hone process and/or oil used or too easy break in procedure-------

Use up a whole can---------don't stop early------but do make sure that it goes into the carb as sort of a dusty cloud-no lumps or streams too big for the carb to mix with the inflow-----

And see if you can get some Brad Penn or Joe Gibbs BREAKIN oil

I still want to see pics of the rocker assy and oil splash shields from the top end