Today, dollar for dollar, is the 318 faster than the 340 ???

And your $3000 budget? C'mon man. If you got a $3000 budget you better be buying a damn gasket set, rings, bearings, Summit cam, and freshening that sucker up. It's 2021 ol' son. You aint getting very far on ANYTHING with $3000.
The most money I have in an engine, including the price of the engine, in my cars today is 1450, and it has aluminum heads. I think 3k would be "unlimited shopping"... LOL