For a strip car, or one that was strictly a play toy to go in a straight line that occasionally is driven on the street, could go either way. For a street car, especially if you want to go fast through corners, the 347 hands down.
That depends on your intended usage. (which you didn't provide)
The voice of non-conventional wisdom would tell me to put the 460 in it, provided you want to spend the extra money to make it work properly.
You'll need heavier springs for sure, and of course the required mounts and headers for the swap. The trans won't fit, and the driveshaft will have to be altered.
Unless you plan to convert over to carburetor, you'll have a hefty chunk in the F.I. and induction for the big engine.
Your mileage will be the stuff of legends......think.....10-12 MPG carbureted, maybe 15-17 injected.
But.....only a few have one (mostly for the above reasons) and (depending on how the 460 was built, and what's inside it) 11 OH ET's right outta the box, 400-500 ft lbs of torque on a stock rebuild.
And THAT is always a good reason for a quick trip to the Walmart to pick up a loaf of bread and some tampons for the wife.
Soon enough this will be you:
" Honey are you sure you have enough tampons?....I can go get you more,...it's REALLY no trouble. I'll just pop down there in the coupe, and be back before you know I'm gone."
The 460 would be cool, but as mentioned by others, you never said what you wanted to do with the car.
You have 'wow' factor with the 460, but remember you will lose most of your accessories.
I am not even sure you can keep the power steering with the 460... and driving on the street with 700# on the front tires, you will want power steering! :yep:
The 347 might be done to death, but their is a reason for that...