surprise for the Monte Carlo
Me too. Got a buddy with a 540 inch 72 Monte that runs high 10's in full street trim and is very streetable. Considering how much cheaper it is to build a Chevy it's no wonder.
As for the OP's question. If the heads are prepped right and it's tuned right and hooks up it should easily send the Monte packing even through the muffs, but I'd go with 3" exhaust. IMHO 2-1/2" is too small at that power level.