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

That’s not true. A forged piston isn’t harder on cylinder walls. Their life span is far better than a cast equivalent. Plus you get the benefit of a far, far better ring pack. That in and of itself makes more power, seals better and will live far longer than the thick rings that come on cheap cast and KB pistons. Again, it becomes penny wise, pound foolish. And if we say let’s do your 3k reman, you are stuck with the cam they pick, unless they have options. And on top of that, you didn’t get the China knock off heads that 318WR said he could do for his 3k build.
Hmm here we go again lol

What silicon content forged pistons are you running? What are the clearance number's from pistons to cylinder? What cranking compression? Personally I have never seen a forged piston motor last to 100,000 miles no matter what. Some hyper's yeah and cast yeah but not forged. All of the forged pistons I have ever seen run loose clearances to allow for the expanding and then they beat on the cylinder walls and wear out faster