Help 360 2bbl tuning

Ok need help trying to make it to power tour in 4 days

Update timing is 14 at idle and 32 all way open
Plugs are white , meaning lean correct? Needles have been every adjustment from 1 1/2 to 6 turns out very little difference
When revs does have little backfire through exhaust

Thinking of rebuilding 2 bbl?

Or swapping to 4 barrels and have a 600 cfm holley carb ?