Back when my 340 had HP manifolds, RPM intake, 650VS carb, 3500 converter, and 3:91's, Scott Brown spec'd me out a cam that was 226/238, 270/288, .489"/.480" on a 112 cl. This has been a great little cam and I still run it today with other upgrades since the cam swap.
But the best single upgrade that I ever made for my stockish 340 was removing the stock convertor for the 3500 unit. (I did not see what tranny you were running, but thought to throw this out there.)