63 linc exhaust

I had my linc 430 rebuilt (.60 over, isky solid cam .505 lift, roller lifters,rockers, custom pushrods, msd ignition box, holley 750 cfm)and now need exhaust. Is the stock 2" too small? Would 2 1/2 " exhaust be worth the extra money?($ 450) Another question , low vacuum (7") with the new cam give some serious hard pedal pressure to stop, not to mention trans shift issues. any easy way to overcome this? Initial timing is another question, how much is too much, idle(now at 12 btdc), 2000 rpm (30 btdc), any suggestions?