Those are my thoughts as well.

1.56 venturi downleg carbs can be a real challenge to "tune the bog out of".

IMO, I think a main body swap to something with a smaller venturi would ultimately yield better results(I'd probably use a 1.400 x 1.750)....... But if I were trying to work around that combo, I would expect to have to run fairly large squirters, and probably a 50cc pump/cam on the secondary side, and I would absolutely ditch the 2.5 pv.
You want to get a head start on the main circuit enrichment when going to wot...... It would get a 6.5 if I were messing with it.

There is a lot of plenum and runner volume in that combo, and not a lot of cubes generating signal.......... It's going to need a lot of help(pump shot) to give the motor something to work with until the main circuit is activated.

Not what you asked, but there is some performance left on the table with that cam, in that combo.