I don't get all the " the 340 is much more expensive, so build a 360 statements".
Fact is, if you look around at all, 340 blocks are easy to find and rarely more than 600-800 dollars.
Even if you find a suitable 360 block for 100 dollars, in the whole scheme of the whole motor build you have maybe 500-700 dollars more money in the 340 build( cost difference of the block)
Many times you can find a 340 short block with steel crank for not much if any more than the price I stated above for just the block.... Needing rebuilt. You pick up the quality steel crank that can take a lot of punishment and is a nice piece.
For a car like yours, for very little difference in money I would i put another 340 in it( or a stroked 340)/416.... No brainer
Edit.... Didn't notice I hadreplied to this thread months ago.... Lol