Replacing my 1 bbl over to a 2bbl. Need help!

BTW, that carb is really ~ 248cfm, at a "performance" manifold depression.....i.e. 1.5"Hg, vs. the 3.0"Hg that 2bbl is rated at. Calculate accordingly....................
The Holley 2300? 350 cfm? 2 barrel?